Meh, pretty good. Very similar to Vista in a lot of ways, but generally seems more polished and less annoying. Doesn't seem like a huge leap right now, but maybe it isn't supposed to be. I like some of the new desktop backgrounds, for what that's worth :)
Still can't stand the Aero theme though, it's just way too busy and it takes up way too much space. Unfortunately, as with Vista, they haven't taken much care with windows classic mode, looks a bit buggy and crap.
I'm curious, what do people here go for, the full pazazz of the modern OS themes, or something clean and simple?
Currently I'm using a custom theme which is very close to windows classic, with the Vista font, and Icons from the tango project ( http://tango.freedesktop.org/Tango_Desktop_Project
). Very happy with this at the moment, about as clean and inoffensive as it gets.