I have the latest Vista installed right now (pre RC). It's actually quite good, I've tested most beta versions and Vista has come a long way from buggy, slow, patched XP version to what it is now.
I haven't really noticed much differences in the audio stack from a user point of view, especially when using professional audio software. I guess that's a good thing.
Ooh, and the flashy graphics are quite cool too, finally some catching up with OS X