After trying it out for the past 24 hours, I must say I’m very impressed by the improvements over version 2. For starters, it has not hogged up to 500+MB of memory after a couple of hours, no crashes thus far too. Besides that, the new location bar (a.k.a. AwesomeBar) is simply fantastic. Most extensions have been updated to work with the latest version but you may have to switch to different ones if they aren’t updated anymore (or do some workarounds). Go get your copy of Firefox 3 here.
While on the subject of Firefox 3, BBspot has an article on it here. And before you go about saying ‘about time!’, BBspot is a satire news site. :P