Launching in October, I'm due an upgrade about August next year so by then the kinks should be worked out. Seems nice to have a good interface that doesn't rip off the iPhone.
A few extracts from the linked reviews.
On one side, we’re still really excited by the prospect of Metro as a viable, clean-slate approach to the mobile user experience, and there are lots of smart moves being made that could lead to greatness.
For as much crap as Internet Explorer gets (less, admittedly, now that the debacle of IE6 is finally starting to fade), we’ve got to say that web browsing on Windows Phone 7 is actually a really pleasant experience.
Microsoft’s done a very good job with a revamped user experience that’s not like anything on the market. Taking a lot of UI cues from Zune HD, the OS is heavy on the visual, using fonts, color and an interesting use of space to make for a solid experience that’s both easy to learn and pleasing to look at.
Summing up, Microsoft’s doing the right things here with Windows Phone 7. It’s visibly differentiated from the competition
There’s a nice level of consistency throughout the apps demonstrated, with the same text and same side-scrolling user interface. That kind of attractive consistency is something iPhone (and Palm WebOS) customers are well accustomed to, but something still a bit out of reach of Android.
Everyone seems to love the keyboard, rating it nearly as good as the iPhone’s and significantly better than Android’s or BlackBerry’s.
One Negative review from Boy Genius Report
The thing is, sometimes when using Windows Phone, things are so minimalistic, that it actually feels a bit too lonely and open. Don’t get us wrong, it’s nice to feel like you’re not constrained to a certain window or foreground app, but at the same time, we can’t help but feel that there could have been so much more done.
Microsoft’s browser is fine, but it’s far from pleasurable to use. It’s not the most elegant browser [...]
We have been playing around with WP7 for enough time, and the OS is well-enough along that we have got a great feel for it, regardless of any minor improvements before the first handset launches. Microsoft has no doubt broken course and gone in an entirely new direction, something that many people wish RIM would do, and we applaud them for that. They have created a brand new mobile operating system packed full of clean, modern, and sometimes even beautiful design elements.