After playing with Windows 8 for an hour, I’m convinced that there are severe design issues in the current state. Furthermore, it is unlikely that Microsoft will think otherwise and fix these glaring errors before Windows 8 goes RTM.
The biggest surprise I had was that there isn’t an intuitively way of quitting or switching metro apps, shutting down the computer, and locating functionality which once was in the Start Menu.
Michael Mace made a 13 minute summary video along with a review and critique of the Windows 8 UI. While I’ve heard comments that his reviews are overly biased and potentially fear mongering, read it for what it’s worth.