Vista RC1
Well I'm up and running on Vista RC1 (build 5600)...and I have to say it is a marked improvement over previous Beta builds.
I felt like the install took longer but the performance, especially boot up/login is much faster. Overall the OS runs faster than previous builds and lots of stuff that wasn't working before seems to be working rather nicely now, e.g. screen rotation on Tablet, Bluetooth.
One problem that I was having was with Media Player and lots of DRM stuff (at least I'm guessing that's what the problem was)...haven't had a chance to try some of that yet.