18 months ago, Microsoft president Steven Sinofsky demonstrated a very early version of the company's next web browser, Internet Explorer 9, establishing right away the product's three core tenets: Performance, interoperability standards, and hardware acceleration. Sinofsky and company also promised they would develop IE 9 at a faster pace than with previous versions, answering criticisms that Microsoft couldn't move as quickly as its competition.

The software giant did pretty well on that last bit, neatly splitting the difference between the somnolent Mozilla and the perhaps-too-fast Google by release the first developer-oriented IE 9 in March 2010, a Beta release in September 2010, a Release Candidate in January 2011 and, now, the final version.

That beta process wasn't just efficient, it was also highly successful: The Beta and RC versions garnered over 40 million downloads, a figure Microsoft says is over twice that for the IE 8 Beta, and represents the company's biggest ever browser beta. Two percent of all Windows 7 desktops worldwide were running pre-release versions of IE 9.

Well, now the final version is available. How are things looking?

Good, I think. And to understand why, it makes sense to examine the main areas where Microsoft improved IE 9: The user interface, performance (including hardware acceleration), and web standards interoperability.

User interface and design

Compared to IE 8, Microsoft's latest browser provides a simple, scaled-down UI that somewhat resembles that of Google Chrome. It still retains some recent and unfortunate IE quirks, like stranding often-need buttons like Home, Favorites, and Tools over on the right side of the window, far away from the browser's navigation buttons. But overall, IE 9 goes a long way towards minimizing the browser UI, providing a bigger canvas for the sites you're visiting.

Microsoft calls this new design a site-centric user interface, and it's mostly well done, though you can of course bulk things up by adding back legacy UI like the Favorites bar, the Command bar, the Status bar, and any number of third party and Microsoft browser toolbars. If you don't, the upper window UI in IE 9 takes up about the same number of pixels as does Google Chrome (minus the Bookmarks bar).

In that upper bit of browser chrome, you'll see some familiar but upgraded elements, including the redesigned Back and Forward buttons, the new One Box, which integrates the old address bar and search box into a single control (as does Chrome), at least one tab, and those three stranded buttons. Since the beta, this area has been cleaned up quite a bit as well, with one major change being that you can now choose to display tabs in their own window-wide toolbar, giving you the maximum amount of space for tabs (while taking up a row of space from the sites you're visiting).

In using IE 9 over the past several months, I've found this new UI to be superior to the old IE 8 UI, unless of course you're a heavy user of Favorites. Microsoft has made finding Favorites a lot more cumbersome in this release, though I should note that it has also added more elegant, Windows 7 integration bits which somewhat mitigate that issue. And of course you can enable such things as the Favorites bar and even pin the Favorites Center to the side of the IE window if you want. Frankly, this is progress, and while I know some will feel stranded by this design decision, I think it was the right one.

Notifications have been completely overhauled in IE 9 as well, and here again Microsoft has cleaned some things up since the Beta and RC releases. Notifications appear at the bottom of the IE 9 window and, as such, are sometimes hard to discover. So in some cases--like a file download request--the notification bar will now actually throb in an orange color to draw your attention if you let it sit for too long.

Windows 7 integration features

Say what you will about standards compliance and hardware accelerated performance (and don't worry, I'll address those topics too) but the best reason to use IE 9, perhaps, is its Windows 7 integration functionality. (IE 9 also runs on Windows Vista, but not XP, but these integration bit are Windows 7 only.) For the time being, finding sites that really take deep advantage of these features may be a bit hard, but more and more are coming online all the time, and as Microsoft has adequately explained to web developers, it's not hard to do so at all.

So with IE 9 you can now "pin" web sites to the Windows 7 taskbar (and Start Menu, though that will be less common) just as you can with application shortcuts. This creates a situation where your taskbar can contain a mix of shortcuts to native Windows applications as well as web sites and services, which, when you think about it, makes perfect sense. After all, each of us uses some mix of applications and web sites each day, and the line between an application and a web app is blurring. (Microsoft reports that Windows users spend almost 60 percent of their time online, so pinning web apps and sites is arguably a bigger deal than doing so for native applications.)

What you get when you pin a site will vary. Sites that do not explicitly support IE 9 in this way will display a very basic icon that doesn't "fill" the entire taskbar button, and a basic, pre-designed jump list with few options.

But sites that do support IE 9 can display a nice high-resolution icon that is very similar to native application shortcut icons and a custom jump list with site-specific features.

Furthermore, pinned sites display in a custom version of the IE 9 window that uses color-coded navigation buttons (automatically matching the site color scheme). Confusingly, these button lack a traditional Home button (which, again, is "stranded" on the right side of the window in normal IE 9 windows) but pick up a new site home button (which, inconsistently, is to the left of the Back and Forward buttons, which need to be pushed right to accommodate this change).

These custom site windows are a good idea, but unlike a similar feature in Chrome, the use of onscreen browser controls results in a less efficient use of space. In Chrome, pinned sites (which Chrome calls application shortcuts) aren't as powerful as those in IE 9, and offer no Windows 7 integration bits, but then they also don't clutter up the UI with browser controls; you get a blank window instead. Now, that's site-centric design.

Ultimately, the Chrome vs. IE 9 debate is somewhat of a wash. IE 9 is more powerful, but Chrome really gets out of the way.

In addition to site pinning and custom site windows, IE 9 provides Windows 7 Aero Snap functionality for its tabs, icon overlays (for notifications, a la an email web app) and thumbnail preview controls, the latter of which is particularly useful to media services (Pandora, Jango, and so on) that want to provide playback controls outside of the browser window.

Security features

With its emphasis on corporate users, IE has always had stronger deployment, centralized management, and security controls than the competition. And with security, in particular, Microsoft has made some interesting enhancements to IE 9.

Key among these is the recently announced tracking protection functionality, which seeks to answer the FTC's call for a "do not track"-type feature for web browsers. As originally described, IE 9 tracking protection would have required users to discover this feature, find one or more third party tracking lists, and then install them in the browser themselves. And I felt this was just too much to ask.

Since then, however, Microsoft has implemented tracking protection in a far more useful and user-friendly fashion. And it could very well prove to be one of the best security features the company has ever added to its browser. Now, by default, IE 9 will maintain a personal list of sites for each user that exhibit tracking behavior. Blocking of these sites is not enabled by default--I guess we can't have everything--but enabling this is simple enough (Tools, Safety, Tracking Protection, Your Personalized List)--and is recommended.

At this point, IE will simply continue monitoring the sites that try to track you and it will prevent them from doing so. But you can take this a much more aggressive step forward and click a link in the Manage Add-ons/Tracking Protection interface, which takes you to the newly redesigned IE Add-ons web site, and from here you can pick and choose from those third party tracking lists to augment IE's protection further.

IE 9 also provides a new ActiveX filtering feature that answers what might be IE's longest-standing complaint: That it is the only browser compatible with insecure and unsafe ActiveX controls. Now, you can simply filter ActiveX controls (again, it must be enabled, but it's very simple to do so), so that none will load by default. As you navigate from site to site, those that do contain ActiveX controls will trigger an ActiveX filtering notification (curiously at the top of the window and not in IE 9's notification bar), letting you enable them on a case by case basis and only for those sites you actually trust. And businesses can of course control this functionality via Group Policy.

IE 9 also includes improvements to its predecessor's SmartScreen filtering and InPrivate browsing features. The SmartScreen filter now integrates with IE 9's new Download Manager, for example, and InPrivate browsing is now available from more locations, including IE 9 jump lists and pinned site shortcuts.

Standards compliance and performance

Here, we get into some of the more controversial bits surrounding IE 9. Microsoft's web browser has never been lauded for its web standards compliance, but the software giant is taking big steps in this release to address those shortcomings. And focused as it is on Windows, Microsoft says that it is providing in IE 9 the best possible performance of any web browser on that platform, with hardware acceleration for virtually all onscreen elements.

Competing browser makers have taken exception to both of those claims.

With regards to standards compliance, even Microsoft offers up an interesting caveat, noting that IE 9 is the most standards compliant browser that it has ever shipped. And that's certainly true. But detractors are quick to point out that the bar wasn't particularly high to begin with, as IE 8 and older browsers were decidedly lagging in this area. These critics also complain, with charts and graphs and antagonistic standards tests, that IE 9 is still lacking behind such browsers as Chrome and Firefox.

Microsoft's response to these complaints is, I think, credible. The company says that the specifications in question--especially HTML 5--are a moving target, which they are, and that these things will be changing for years to come, which they will. It also claims that IE 9 performs well against the subset of standards that today's sites are actually using, and it offers up its own tests to prove that point.

But I think where Microsoft makes its strongest case is in the notion of "same markup," it's goal for web developers to only have to write to a single spec that will work equally well--or at least "correctly"--across all major browsers. And to arrive at this place, it has submitted almost 3,000 individual browser tests to the W3C, which oversees these standards, in hopes of creating a way for all browser makers to properly test compliance.

What users care about, of course, is that their browser "just work" and that the web sites they visit render correctly and quickly. To the former, I'd say that IE 9 pretty much works as expected, though I've seen some odd small font issues on some Google sites (like Gmail) and occasional column rendering problems on random sites. This is a work in progress, but I will say this: IE 9 certainly works better, much better, with regards to standards than any previous IE version, just as Microsoft claims.

Its performance claims are equally justified. IE 9 is fast, blazingly fast, and you don't have to visit any of Microsoft's (or Microsoft's partners') many demo sites to see this is so. That's because IE 9 takes advantage of the native hardware acceleration abilities of Windows, which utilizes the GPU, not the CPU, for most onscreen rendering, dramatically speeding performance and quality.

Now, other browser makers claim they can achieve similar levels of performance, and they're working to do just that, not just in their Windows browsers, but on other platforms as well. I suspect they'll do OK. But focusing just on IE 9 right now, it's pretty clear that Microsoft's push to hardware-accelerated, well, everything, was the right move. Graphics, text, audio, and video is all hardware accelerated, allowing the browser to stop limiting itself to roughly ten percent of your computer's abilities. Now, Microsoft says, IE 9 can take advantage of the other 90 percent as well.

Since the Beta, one big change is that the hardware acceleration features work better on low-end machines as well. So you should be able to see a big difference no matter what type of PC you have.

Installation and availability

Microsoft made Internet Explorer 9 available today via the normal download mechanisms, with separate versions available for 32-bit Windows Vista, 64-bit Windows Vista, 32-bit Windows 7, and 64-bit Windows 7. (The 64-bit versions apply to the OS only; the browser that is installed is a 32-bit application regardless.)

In an unexpected move, IE 9 can now be installed without rebooting your PC, though doing so requires you to allow the installer to shut down virtually everything running on the system, including Windows Explorer. (If you don't wish to do this, you'll just need to reboot before you can run IE 9.) I believe this is a first.

Final thoughts

Once you jettison all the hyperbole and posturing, especially from the suddenly defensive competition, you're left with a very simple decision here: Do you use IE 9 instead of some other browser? I have a couple of bits of advice along those lines.

First, if you're using an older IE version, switch. IE 9 is faster, more secure, more standards compliant, and more efficient than any previous IE version, and if you're using Windows 7, it offers the best OS integration features around. In fact, for all the hand-wringing over whether it was wise for Microsoft to integrate IE into Windows when it did (it wasn't), this release points very cleanly to how this integration can be well done. IE 9 is a nice complement to Windows 7, one that make web sites work more seamlessly within Microsoft's core OS.

If you're using an alternate browser, like Chrome, your choice is a bit more nuanced. Google, Mozilla, and other browser makers are racing to add hardware acceleration features to their products, and most of these browsers already offer great standards compliance (even if a lot of that is aimed at achieving high scores on manufactured, non-real-world tests). Some, like Chrome, even offer very basic OS integration features, though none come close to what's available in IE 9.

Most users are advised to run at least two browsers regardless, and on that note, one of those browsers should be IE 9. Whether it becomes your de facto browser is a matter of choice, but I'm switching to IE 9, for now at least, to see whether this is a long term recommendation. My only issue, currently, is that I use Google's Gmail and Google Calendar services, and these sites don't work quite as well in IE 9, especially in pinned site form. So these taskbar shortcuts are for Chrome on my own PCs, though I'm using IE 9 elsewhere.

Ultimately, Microsoft's most impressive feat here is that it's made IE 9 a real contender. Previously, Chrome was my overwhelming choice for web browsing, with my IE usage slowly falling off to a limited selection of Microsoft and Microsoft-oriented sites. With IE 9, this is no longer a requirement, and if I wasn't so invested in the Google services I would be able to switch entirely.

Another important bit to consider is Microsoft's new emphasis on rapid development. The company has suggested that it will continue with this schedule post IE 9, but whether future improvements take the form of updates to IE 9 or a coming IE 10 release is unclear. Either way is fine with me: It's nice to see that some parts of Microsoft, at least, understand the need for rapid innovation in a fast-moving market. They're doing the right thing.

Internet Explorer 9 is highly recommended, especially to Windows 7 users.