I really don't appreciate the thought by Mozilla that I don't understand URL bars or don't know how to use them. It's insulting to think that by now the vast majority of computer users don't understand almost everything about them. It shows where you are; if you type something and hit enter it tries to go there; some URL bars act as search bars as well; it's not that difficult to wrap your mind around. Besides, I would much rather spare those 50 pixels or so for easier access to it.
I'm not fond of Ubiquity so far, either. It's all personal preference, and I'll prefer using a more traditional-looking browser if I can't eventually undo all these design changes Mozilla wants to implement. The moment I have to use a third-party add-on to restore the look and feel I want is the moment I change browsers. I'm only sticking with Firefox now because of Ad-Block and one or two other plugins.