I just installed the Windows 7 RC. I'm kind of skeptical, but it seems to be doing better than Vista. Of course, Aero is beautiful, but I'm still undecided as to whether or not it's helpful. They've adopted some styles from Mac OSX as well as Ubuntu. Of course, Windows gadgets are Widgets from OSX, and the "View Desktop" button on the taskbar is straight from Ubuntu. However, the taskbar is a whole lot nicer, admittedly. Right clicking on programs running brings up a small menu of options and a list of items recently viewed with that program (if that applies). That's pretty handy. And there are very well executed thumbnails, and if you hover over a program on the taskbar, after about half a second, all programs fade away on the screen except for that one. I find it really pretty handy. I also like that balloon tips are not popping up everywhere.
My biggest complaint so far is that, by default, IPv4 and IPv6 protocols are running on each network card. This caused me problems, and I had to actually disable IPv6 to get connected to my router (which isn't that old). I'm not sure the average user would know this fix.
Anybody else use it yet? What do you think?