Here's a look at Firefox from the perspective of one of the Internet Explorer UI designers who made the switch recently. He's got some interesting thoughts on tabs, stuff I never thought about before; for instance, he makes the point that since each Firefox tab gets its own back/forward stack, the tabs really ought to live above the navigation toolbar, not below. Same goes for Reload (since it doesn't reload all the tabs, does it?) and the address bar. Home can stay above the tabs, though, since it's global. Come to think of it, that's how Opera does it. Hmm.
I can't believe the Find UI tops his list of problems, though. The first time I hit control-F in Firefox, I just about splooged.