9 out of 10 so far. The only problem I have had is trying to triple boot with Linux and Solaris (it's easy to do via Grub, but then Windows Backup doesn't work and Windows won't sleep). Got Windows and Linux booting, but Solaris is a bit of a PITA.
Web browsing seems much snappier than the RC or my Linux installations.
Edit: I should have added - those Luddites who are staying with XP are making a big mistake. Windows 7 is so much better than XP; and at £45 it was a snip.
Yeah I've been running my server on it at home for a while now and it seems very good. For some reason the wifi on the server (it's actually a cheap laptop, lol) only runs at a few Mb/s but that might be a driver or card issue.
I run Vista on one of my development machines at work so I might upgrade that but actually that's been pretty good. The UAC isn't half as intrusive as 'the mob' would like to claim. It annoyed the hell out of me on one of the test machines but then I was manually messing about with the contents of Program Files\ and modifying security settings. Hardly surprising that it got arsey about it so I turned it off in the end.
I did find vista pretty much ok, memory usage was a bit much, but i did have 4gb of ram to play with. I turned UAC off in the end, even with the sp1 making it less intrusive.
UAC on win7 is much better.
Things i don't like like about win7
-they altered favourites on explorer and i preferred how vista did it

-homegroups sucks because of its offline requirement. I wanted to map a linux box into the homegroup, and win7 wouldn't have none of it.
-win 7rc trashed the bootloader.
- 70 folder limit for the startmenu sucks