I ran the RC on my laptop for months, and it really increased performance and reliability over Vista by a large margin. Vista BSOD'd EVERY TIME I BOOTED. I mean literally every time. So far 7 has crashed 4 times, and I think they are hardware issues (of course DELL disagrees).
I have now upgraded all three machines to 7 and I love it. I did not like the file manager originally, but I am getting used to it, and the other features far outweigh that. Mostly, I like that it is lightweight, fast, and unobtrusive.
It really impressed me when I hooked up my 13 year old HP 722c printer, and it recognized it, ID'ed it, and installed drivers and configured everything in about 20 seconds. Every piece of hardware I have hooked up has connected flawlessly and automatically. Vista would not play with most of them, so 7 is a great improvement.