I have Vista Home Premium and so far I like it. A few of my games don't work but all-in-all I like it. Nevertheless, I'd consider waiting 6 months. My computer blew a hard drive and a graphics card all on the same day so I thought I'd give Vista a whirl.

There are some compatibility issues with drivers and software. Comparing user experience from the upgrade from Windows 2000 to XP, it's a bigger more pleasant change. The Ultimate Edition has some nice features for system backup and encryption. I also like the new implementation of Windows Media Center; I have an Xbox 360 hooked up as a Media Center Extender and it was much easier to connect to this time around and stream live TV. It's no wonder Microsoft is owning Sony in the consoles wars (at the moment - next to Nintendo of course).
-=Ole