I used the beta and the RC on my old Dell Inspiron 9300. Low ram, low HDD space, no graphics card, and it ran very smoothly with the Aero theme. Now I have the full release on my desktop (4GB of ram, 900 GB of HDD space, GeForce 7600 GT XXX) and it runs amazingly well. I had XP x64 on this machine previously, and 7 blows that out of the water. No major issues whatsoever. Only issue I had was the wireless card drivers didn't come packaged with it. A quick forage through my CD/DVD case found the old XP drivers for that card and now all is well.
The only thing is, on the Inspiron, it slowed down considerably after a month of use. Not sure if that was worked out before the official product release, but it's been holding its own very well for the last month on this much more powerful rig.
EDIT: I have run a few graphics intensive video games on the rig, and no BSOD has resulted.
2002 Chrysler 300M Special, DSB | 2007 Dodge Charger R/T Road & Track, BB
2000 Dodge Intrepid SE - Champagne | 2001 Dodge Intrepid ES - Sapphire Blue Pearl | 2003 Pontiac Grand Prix Ivory