I used it for a few days and I didn't have any severe problems. However, it was a lot slower than XP. I'm hoping they increase its performance before shiping the final version.
I own a Celeron D 2.66 @ 3.36, I use clockgen to overclock in vista and most programs work with them. I get 1% cpu when I idle. Its every stable and no program didnt Fk up on me. Its just how you use vista is the way its unstable.
Counter Strick 1.6 NON Steam work on Vista beta 2. Im hosting my server on Vista and you think vista is unstable. No its not