It's funny, when vista came out, everyone said it sucked but I thought it worked just fine. Now that windows 7 is out (kind of) a lot of people are talking about how great it is and I really don't like it.
For me it actually boots slower than vista. And on vista I have far more things load when it comes on. So I don't know what's up with that...
And I really don't like the taskbar that much. I think it's kind of interesting and useful, but I prefer the old taskbar. I like to see all the windows I have open. And it just looks a lot more streamlined than in windows 7.
Take all this with a grain of salt though, because I haven't really used it that much at all since I've installed it, and I do realize that this is just beta. But I still don't really like windows 7 that much.
I've had no problems with vista ever, and I've been using it for about 2 years, So I'm very comfortable with it. I don't think I'll be upgrading to Windows 7, because so far there isn't anything I see in it that I really have to have.