I just upgraded this site to WordPress 2.5 Beta. So far, everything appears to be working just fine.
And since I know lots of people will ask, I checked my plugins, and most of them (HeadMeta, Text Filter Suite, and Easy Gravatars), work just fine. The one that doesn’t work is Theme Preview. When I can find time, I’ll try to figure out why.
The official WP release is slated for March 10.