Been using FF 2.0 for a few months now, but I really didn't see what it had to offer until I used a theme & many useful extensions.
Decent basic how-to article
Firefox 2.0 is
so good, imo, that at this point I plan on never going back to IE if I don't have to. The only reason I use IE is if a page doesn't work in FF, such as Windows Update (imagine that!)