I tend to avoid Winblows whenever possible, but that's impossible if you want to play games. I use 32-bit build 7201, and I've found Windows 7 to be a huge improvement on Vista (which made me want to die). It's faster, less error-prone, and far nicer to use from what I've seen, and much more like XP, which IMHO is a far superior OS to Vista.
In fact, the only problem I've encountered so far is an incompatibility with online games running Punkbuster anti-cheat software, including the Battlefield series, but this is (surprisingly enough) not actually Microsoft's fault: Punkbuster are just too lazy to bother adapting their software for use on the beta version.
Oh and one other slightly strange thing I've noticed... On some websites that try to check my OS, it shows up as Windows NT. Weird.