Well, it's just Windows Mobile. Nothing special or different about that. The demo videos that were going around when the prototype was shown don't really manage to convey the suck that is WinMo, and it looks like it runs Pro, which means you have to poke at the screen with one of those teeny, tiny sharp sticks. The zoomy icon thing everyone (including me) was excited about turns out to be nothing more than a launcher. As soon as you get one layer deep, it's back to a UI that looks like shareware from Windows 3.0. After getting used to the iPhone, I don't think I could ever go back to using something like this for my every day device.
If you're resigned to the OS, though, it looks like a really sexy form factor. That costs 2 1/2 iPhones.