Bumping this thread, I have win8 - release version (not to be confused with release candidate). It's basically win7 with metro. I wouldn't recommend upgrading until the next service patch comes out, but if you're like me and don't have any sensitive operations on your computer it's only $30 or a tad more for the standard edition.
Metro is meh. It looks very pretty, but honestly everything is just aesthetics - task manager has been changed which at first I disliked, but am now getting accustomed to. I've noticed a significant increased speed in booting from shutdown, no significant changes (atleast with my machine) in booting from hibernation. Took me longer than necessary to figure out how to shut down.
Most games are compatible. I don't think much has changed in the graphics side other than WDDM v1.2 and DXGI 1.2, but I'm not experienced with either of them. Haven't had complications updating my AMD card's drivers, unlike what I hear with the Nvidia cards.

Anyway, ask me anything. I'm going to put up pictures of metro~
Edit: I didn't notice that "hibernation" was removed. What I was using was "sleep".