I've now completed the upgrading of my machines to Windows 7 and have been using it for a couple of weeks. Overall, I am very impressed. Both my desktop and laptop seem faster, start-up times are much shorter, and the graphics seem slicker. I like the "make this window half the screen" feature on my laptop, but it doesn't work so well on my multiple-screen desktop machine. I'm getting used to the new style taskbar - I started not liking it, but after a week or so I warmed to it; so it's probably just one of those things you learn. (I'm still puzzled by why the notification area icons are all white though!)
But I think the Windows team have done a great job. Go 7!