I am not a Microsoft fan at all, but I guess I fall on the side of those who are impressed with the WM7 interface. To me it's the most innovative UI I've seen in a long time. I'm a fan of the N900, but basically it's trying to simplify and translate a computer desktop UI paradigm to a phone. It remains to be seen (i.e. with Maemo 6) whether that will have much mass market appeal.

The iphone, on the other hand, is basically just an app launching device, with a slick interface. And if you think about it, Apple has not fundamentally rethought it's design grammar since the original launch of OS X. It's getting dated.

WM7 is an attempt to really rethink what people want from a pocket media/phone device and how they interact with it. The UI is organized around the sort of activities (social networking, games, calls, email, web browsing, etc.) that people do on these devices, rather than trying to provide a basic platform from which these activities can be launched. The level of integration of activities with each other is impressive.

And it seems like Microsoft is moving beyond even the concept of applictions launched against a desktop in general. Even the question raised by some about multitasking I think is perhaps to misunderstand how it's not relevant to a UI like this (which remembers the state you left things in and relaunches them that way).

Honestly, to me the WM7 interface (at least what I've seen so far) makes everything else look clunky and dated. I think Microsoft may have a paradigm shifting platform here. Of course, that could also lead to it failing, if it's just too different for people.

Also, people say the Zune Pass is amazing. $15/month for unlimited music. This has real potential to go head to head with iTunes in a way no one else has. Yes other people offer this kind of service, but not so seemlessly integrated with a device.

So I find it very interesting. I'm not surprised that Microsoft pulled this off. They've had a lot of very innovative ideas floating around as basic research for years, this is just the first product they're actually putting some of these ideas into.

All that said, Microsoft is so proprietary I can't ever imagine wanting to get locked into their universe of products and services.