So far, I'm pleased and impressed with this version over Vista. Vista set the bar sort of low so to reach beyond that probably wasn't to much to ask.
I have win7 on my acer netbook for 3 days now. So far so good. I think my use of the OS features though is a lot less than some of the descriptions I see here.
Compared to XP though? time will tell. My netbook had XP Home on it from the factory and so far Win7 seems a little slower, which I expected, but it's not enough to for me to be too vociferous yet. The 60 second lag someone mentioned previously is about the biggest complaint I have so far.
Once i get it on my dual monitor desktop, I may have more to say...