I really, really like Windows 7.
I despise Microsoft with a passion. For the last 15 years they've come out with only very few exceptional programs and software, imho, and charge a good deal of money for them when they should have cost far less. Most of their operating systems had significant bugs upon release and suffered from networking and program compatibility issues for years afterward. However, I have not had a single significant problem with running Windows 7. It is a nice system and runs seamlessly, even while performing multiple processor intensive tasks. For example, at one point I was ripping a CD, installing FallOut3, downloading a video (via torrent), playing a movie, and surfing the web, and all without any hiccups in performance whatsoever. I was absolutely amazed at how well the system ran.
I've never used Vista, so I couldn't compare the two. However, I do believe that Windows 7 runs much smoother and faster than my XP Pro SP3, even with XP running in the classic settings.