Compared to the app-centric smart phone platforms of the day--iPhone and Android, primarily--the Windows Phone 7 user interface, called Metro, is a breath of fresh air. It's not just different to be different but is rather the result of actually looking at how users use their phones rather than dictating how it has to work. (Cough. Apple.) So while a Windows Phone is immediately recognizable as a modern smart phone, it does do things a bit differently. Better, usually, but not always.

Lock screen

Aside from the out of box experience, your first peek at the Metro UI starts at the lock screen, which provides some hints about the bubbly Windows Phone experience underneath. As with the Zune HD, if you just tap the screen, it will scroll up just a bit to let you know that an upward swipe will unlock. Glanceable information can be found at the bottom of the lock screen, including your next appointment, the number of unheard voicemails, unread text messages, and unread emails, though there's no way to go directly to any of those experiences from the lock screen, as you can from Windows Mobile 6.5.

Windows Phone 7 Review
A beautiful, customized Windows Phone lock screen.

You can customize the lock screen with your own photo, providing a nice personalized experience. This isn't unique to Windows Phone, of course, but the beautiful typography Microsoft uses here really makes a difference.

Start screen

Once you get past the lock screen, you can feast your eyes on Windows Phone's most controversial UI feature: the live icons on its Start screen. Microsoft designed this display, which scrolls only vertically, to hold only those live icons--or shortcuts, as we'd call them in Windows--that really matter to you. (A separate screen listing all installed programs can be accessed by swiping right to left.)

Windows Phone 7 Review
The Windows Phone Start screen (with customized green on white theme).

Some have described this screen as bland, because it features large, flat, and monochromatic tiles. Those people have never actually used Windows Phone. Yes, the live tiles could be a bit more configurable--you can choose color schemes, including between black and white backgrounds, but can't specify different colors for different tiles, for example--but their usefulness is hard to communicate in a static screenshot. The point of these live tiles is that they can be dynamic, and animated, and can update on-the-fly. In real world use, as it turns out, they're quite handy, and much more useful than the static grid of small icons one sees on the iPhone.

Apps--and other items, like web pages, individual contacts, and OneNote notes--can be pinned to (and removed, or unpinned from) the Start screen in the same way that shortcuts are pinned to the Windows 7 taskbar. They can also be rearranged, so you can organize the screen in a way that is most useful to use. This variety is key to the success of the Start screen, because it allows you personalize your experience and promote the most valuable tiles to the top of the screen.

As mentioned previously, live tiles are dynamic. Consider the iPhone to understand the difference. On Apple's much-lauded smart phone, each icon is represented by a simple, small icon. These icons can include just one bit of dynamic information: A number overlay. So the email app might display a small "3" in a circle on top of its icon to represent the 3 unread messages that await. But that's as far as it goes.

On Windows Phone, live tiles can display all kinds of information, and it varies from app to app. So the Phone, Messaging, Email, and Marketplace tiles all work much like iPhone icons, displaying just a simple number when appropriate. But other apps do more. The Calendar tile, which is "double wide," occupying the full width of the Start screen, displays the name, location, time and date of your next appointment, providing you with a glanceable update so that you often won't even need to start the app to find out more. (As you have to do on the iPhone.)

Windows Phone 7 Review
The Calendar tile provides glanceable info about your next appointment.

Other tiles go even further. The People and Games tiles provide fun, distracting animations. The Pictures hub tile--which, like that of Calendar, is double-wide--is customized with a favorite photo. The Music + Videos tile is customized, automatically, with artist imagery (of the artist you most recently listened to). Your "Me" tile, which links to your own information, cycles between your contact photo and your most recent social networking update, which could be a photo or text. And of course third party applications are free to customize their live tiles as needed.

Windows Phone 7 Review
The Me tile animates between different states, shown here.

Windows Phone 7 Review
The Pictures tile customized with my own background, and the Music + Video tile automatically customized with imagery of the last musical artist I listened to.

The result is a wonderful, dynamic, and animated experience that makes the tired iPhone UI look old fashioned by comparison. This is one area where the critics are wrong: The Windows Phone Start screen with its live tiles is one of this platform's biggest strengths.

Hubs and apps

There's been a lot of silliness written about the Windows Phone hub model, with some pundits claiming that these interfaces will only confuse users, and others arguing that it represents a sea change in the way people use smart phones. The truth, as always, is somewhere in the middle.

Put simply, Windows Phone supports two kinds of apps. The first are just apps, and they're what you're familiar with on the iPhone and other smart phones. Apps are apps. They are generally single screen, standalone experiences that exist for a single purpose. For example, a Twitter app, a Windows Live Messenger app, or a New York Times app. (Games are also apps, of course.) Windows Phone apps work like other smart phone apps. You tap a live tile or icon to run the app, the app takes up the full screen, and you eventually back out of the app to do something else.

Windows Phone 7 Review
A couple of (built-in) Windows Phone apps: Calculator (left) and Calendar.

Hubs are just a second type of app, or "super" apps. They differ from traditional apps in three key ways: They are multiscreen panoramas that require flicking, or scrolling, from left to right; they integrate with various services and present them in a single cohesive UI; and they are extensible, meaning that they can be made more powerful through the addition of third-party downloads. (In the initial shipping version of Windows Phone 7, the extensibility of hubs varies wildly from hub-to-hub.)

Windows Phone 7 Review
The Office hub.

The multi-screen, panoramic UIs presented by these hubs is the most immediate and obvious differentiator. And yes, they can be beautiful: The Pictures hub, in particular, is just a gorgeous UI.

Windows Phone 7 Review
The Pictures hub (mockup).

Windows Phone 7 ships with several hubs, including Games, Marketplace, Music + Videos, Office, People, and Pictures. I'll examine these in turn elsewhere in the review. But to understand why this kind of UI is useful, consider the Pictures hub and how people interact with photos on other phones. I'll use the iPhone as the obvious example. And kicking boy.

When you want to enjoy photos on the iPhone, you as the user are responsible for knowing where those pictures can be found. The iPhone has a handy Photos app, but that app only contains photos you've synced manually over USB from iTunes, and pictures taken with the device's built-in camera. As an Apple fan, you may utilize MobileMe for photos sharing online; if so Apple supplies a separate MobileMe app. Google Picasaweb user? You can choose from multiple apps. Facebook has its own app. So does Flickr. And SmugMug. You get the idea. All your pictures are as spread out on the iPhone as they are in real life. You have to go in and out of apps, remembering not just which apps to use, and where they are on the various home screens, but also which services contain them. Apple's little productivity wonder can do nothing to make this easier.

Windows Phone, in sharp contrast, works the way you do. It simply provides a single interface for photos, called the Pictures hub, which aggregates photos from multiple locations into a single, cohesive, and beautiful interface. And these aren't just your photos. It also features photos that others have shared with you, via services like Facebook, Flickr, and many, many others. (Curiously, MobileMe isn't on the list. Maybe someday.)

This isn't just an improvement over the iPhone, it's a revolution of usability that shows how broken Apple's apps model really is. But, as with everything else in life, the hub model isn't perfect. First, hubs aren't universally extendable. So while it's pretty easy to find add-ons for the Pictures and Music + Videos hub, you won't see anything like that for, say, the Office hub, at least not right away. Second, the degree to which developers can extend hubs also differs. So it's possible for someone to write software that allows photo editing, for example, and this can be deeply integrated into the Pictures experience. But music services that tack onto Music + Videos are largely relegated to third tier status via a special "Marquee" pivot.

Still, hubs are an improvement. And for those solutions that simply must be standalone, Microsoft offers the normal app experience as well. In this best of both worlds situation, Microsoft comes out on top, well above the dated iPhone UI, and even somewhat better than Android, which does at least offer some interactive desktop widgets.

Speaking of apps, one of the big concerns many have voiced about Windows Phone is that it could suffer the same fate as Palm's (now HP's) excellent webOS and be supported by very few third party apps. This is most definitely not the case. Windows Phone is already supported by over 1000 apps and games at launch, and Microsoft is adding several hundred more apps each week throughout 2010. And these aren't just crapware apps (though they're in there too): Some of the notable launch apps include Facebook, Foursquare, IMDB, Adobe PDF Viewer, YouTube, Twitter, eBay, Netflix, and Amazon Shopping. And before the end of 2010, you'll also see Amazon Kindle, ESPN, AP Mobile, and many, many more. There are already dozens of excellent Xbox LIVE games in the catalog as well. This is the real deal.

But wait, there's more

In addition to the obvious UI elements, there are a number of other user experience features that bear mentioning.

Windows Phone includes integrated voice command functionality, allowing to start applications and, more important, dial the phone by voice. (To enable this feature, hold down the Start button for a second.) This utilizes TellMe technology and is surprisingly effective. So I can call my wife by saying "Call Steph at home" and it actually works. The application launching stuff is a bit simplistic ("Open calendar" and so on) but it can also be used to launch searches. Say something like "find seafood" and Bing search opens up. Not too shabby.

Windows Phone 7 Review
Windows Phone voice command.

Speaking of Bing, search is deeply integrated into Windows Phone and is context sensitive. From the Start screen, you can press the hardware search button to launch the Bing search experience, which is of course location aware. But if you tap this button in other situations, it will react accordingly. For example, you can use this button to find text in a Word document while using the Word 2010 app, search for contacts in the People hub, find music in the Marketplace from Music + Videos, and so on. In this area, Microsoft's offering is roughly on par with what's available in Android, and well ahead of the iPhone.

Finally, one of the neatest things about Metro is that it gets out of the way. With Metro, your content--i.e. what's important to you--becomes the UI. When you look at things like the People hub, Pictures, Music + Video, or even the fine typography in the email app, you see how this works. Other smart phone OSes are all about UI. Metro reverses this trend and puts you--and your stuff--in front. Frankly, that's the way it should be.

Next up, Part 5: Windows Phone at Work...