John Gruber has written up a detailed comparison of the Firefox 3 and Safari 3 UIs.
John nails many of the things that are frustrating about using Firefox or Camino when you’ve come from Safari (or even other bundled OS X applications.) People get really bent out of shape about interface chrome that “looks” like Mac OS X but I don’t see nearly as much effort put into working like a Mac OS X application should.
I would like to point out that there is a plugin called Fission for Firefox that will emulate the Safari style progress bar.