Check my past history if you like; I'm no astroturfer. Still, I'm not going to try to convince you otherwise on this particular topic -- really, it's better you judge for yourself in the first place. That's why RC1 is downloadable.
I am, however, going to say that my experiences so far have been pretty smooth and stable. I've only got an Athlon X2 5000 and 2GB of RAM, but it runs a whole lot better than Vista did on this hardware and actually seems to approach XP speeds in terms of feel.
I HAVE had some problems, though. It doesn't seem to like my bluetooth USB device for some reason. I imagine putting BlueSoleil back on would make a difference but I was kinda hoping the built-in drivers would suffice.
I really need more time to be 100% certain, but things are definitely looking up compared to the clusterfuck Vista ended-up being compatibility-wise for me.