Well, this is a shock to me - it's actually pretty good! I installed it a rather unconventional way (inside a VM but using an actual partition) then booted it natively, all my hardware got recognised and drivers installed. The only thing I needed to do was update the nvidia drivers since there's still no OpenGL support in the Microsoft ones. App compatibility is pretty good, the only thing so far that has caused trouble is Chrome, but that was solved by a command line argument in a shortcut (and probably fixed before RTM anyway)
The "Action Centre" isn't really obtrusive at all. It's only bugged me once about the fact that I've not been bothered to check for spyware yet (well, scanning now) and that was right on boot.
And I like the new start menu and taskbar. Really, I do. It's rather intuitive, you hover over one of the window previews and all the rest of the windows become transparent except for the shadow to show placement.
It's got a bit more eye candy too - transitions etc, but it's actually performing a lot faster than Vista ever did on this machine - the hard drive isn't mashing about all the time (I have 8GB RAM - I should hope it's not). RAM and CPU usage are both down on Vista and it actually feels like a much more polished and finished product. IMO this is what Vista should have been to start with.