If you’re an existing Office 365 business customer as I am, I assume you’ve seen the many warnings that Microsoft has delivered via email: You are or will soon be upgraded to the new version of the service. Here’s the first in a series of articles describing the improvements in the new version of the service.

I’ve written about the new Office 365 for business offerings already, and of course I’ve covered the exciting new Office 365 Home Premium offering pretty extensively too. But what I’d like to look at today is the upgrade for existing customers.

My own account won’t be upgraded until April 20. But since I do have access to a new Office 365 account as well, I can do a bit of compare/contrast over time to see how the two versions stack up, from both management and end user perspectives. Plus I’ll also have some advice for small business customers.

But first, let’s sign-in.

It may seem odd to highlight what is essentially a log-in screen, but the first bit of new UI that existing Office 365 business customers will see is the new sign-in experience. This new UI is perhaps more impressive than it seems at first glance. Sure, it’s prettier. But it also adapts automatically to different screen resolutions and device types. So when you sign-in to the service from your PC or tablet, you get a nice full-screen experience that is optimized for touch on those devices.

Office 365 login

Sign-in on a smartphone, however, and you get an experience that is more tailored to the relatively tiny screen real estate. In other words, this one is all business.

office 365 smartphone login

The new sign-in works across Microsoft services—including Windows Intune (PC and device management and Window Azure, in addition to Office 365—and with federated on-premise identity infrastructures. In the former case, it just works: Sign-in once and you can move between the services. In the latter, that means being seamlessly redirected to your own organization’s sign-in page.

On subsequent sign-ins, you can choose to remain signed in. If you do, you’ll be able to tap on a user tile rather than manually input a password on subsequent sign-ins. (Don’t forget that policies via Intune or other management infrastructures can help protect the PC or device outside of this sign-in.)

More tomorrow.