I've switched to Firefox 3.0 beta 2 a couple of weeks ago because I've been frustrated by the constant lockups the browser gave me. Firefox was fine when I first started using it around version 0.x - 1.x. Sure, it did have some security issues, but the development team would quickly fix it up as soon as they were discovered.
Much (virtual) ink have already been spent discussing this issue on other forums, so there's no need to enumerate my problems here.
Firefox 3 beta 2 is cool, and I no longer experienced constant lockups unlike before. It would crash, yes, but only rarely. Too bad the Web Developer extension isn't available yet on Firefox 3.
Anyway, I'll be trying the nightly Firefox 3 build (is it on beta 3 yet?) for Mac OS X. It apparently has a new look, but I don't know if it already has native Mac controls. They promised that the final version would have one. Oh well, I'll wait and see.