The UI doesn't follow a conventional way how people use UI in any form of mobile devices. There are differences in IOS, Android, Blackberry and PalmOS but those differences aren't huge. If you use either of those devices/OS who should be able to pickup any of the other devices relatively easily. At least this has been my personal experience with Android, IOS and WebOS. What Windows Mobile 7 is doing is a fundamentally different way of how you use a mobile device. You could argue that when IOS was first introduced it was also a different way of how people uses mobile phones. But it was different in the sense that it was not confusing, it was very intuitive.
In contrast Widows7 mobile UI is a confusing mess and very bland to be honest. There no "Wow" factor. Who thought big blocks of animated tiles taking up huge screen real-state to be a good idea? I think this is also a good example of different design philosophy with MSFT and Apple. IOS with its new update introduced folder with the goal of giving you more screen real-state so that if you have a lot of apps you don't have to keep sliding and MSFT adds huge block of tiles (and animated!) that will require you to slide around to find what you need.
It would have made an interesting showcase for concept design that car manufacturers always make, but I don't see this being much practical at all.