I'd have to say that the jury is out as far as IE7 being as good as FF is concerned. I figure we'll know if it's as hole-ridden as IE6 within 6 months or so.
It is already known to break many sites (especially poorly written intranet sites that depend heavily upon MS-Specific IEisms). We've experienced this in my office already. Thank G-d I don't have to deal with that crap.
woeks great on all the MM sites i have visited lots better than FF actually(sometimes i have to open IE6 to watch some videos because FF refuses to play them no idea why weird sites like yahoo and stuff) I only tried IE7 RC1 for about 2 weeks but it worked ok, then i was messing around with something and had to reinstall my "disk image" ;) be carefull when you're messin in the registry! :P