Decided to try the beta.
Quite like it. Very fast, looks good, seems stable, etc. Don't know if it will tempt me away from Chrome though.
EDIT: No, don't think it can.
Don't like it's font rendering. Bold and fuzzy. Looks nice, especially on forums, but it's a bitch to read. Chrome uses ClearType, which is so much easier on the eyes.
I don't really like the annoying orange button thing at the top left. Also don't like that you can't see extensions unless you enable the ugly bar at the bottom. I'm not really a fan of the split address/search bar. It still only loads one thread so can't make use of my CPU properly and if something crashes the entire thing falls over. On top of all that it's slower than Chrome in general day to day browsing too.
But damn, hardware accelerated browsing is SWEET. Too bad it has no real use what so ever. Might try it on my laptop though...
EDIT 2: Just tried Chrome 9 beta. It's even faster (!) and has the hardware accelerated thingie too. Sorry Firefox, you fail