Metro is a nice interface for both tablet AND desktop--or maybe I should say, it CAN be.
Having tried the CP, I know when I say that Metro is a disaster right now. It is way less flexible than the desktop when you can just position multiple windows next to each other in any way or fashion you like.
Stuff is hidden away where you don't expect it is another problem.
Multi-tasking with Metro is somewhat shrouded. We don't know what we can let Metro apps do in the background. Can we compile stuff, can we defrag stuff, can we just let apps load in the background, etc?
The final problem is that all Metro apps are too simplistic. They don't need to be. If they end up too simplistic, power users will just ignore them and the holy grail that is Metro will fail, which it must not do. Remember that Metro is not just a UI; it is based on the new WinRT platform, which will make it easier to develop consistent experiences and get rid of old nuisances such as extremely ugly UI, focusing stealing applications, noisy applications that pop up messages out of nowhere, and more.
NEVERTHELESS, it is pure foolishness to say an OS is bad when you haven't tested it. After you've tested it, you have the right to say so. XP isn't going to stay around forever, anyway, and good riddance--every XP computer out there puts all other computers at risk due to old buggy, insecure code.
So all the naysayers out there - go try it out, then come back complaining. Perhaps it might enlighten you and make you wiser in what is true and what isn't.
And let's hope Microsoft fixes Windows 8 before it ships.