I love it. The status bar struck me as weird cruft that was irrelevant the vast majority of the time. I've been using it in aurora and beta for a while now and I quite like the screen real estate.
It's not a new feature, either. The statusbar has been a "only when hovering on a link" for many releases.
Yet another feature copied from Opera....
At this point some of the most beloved browser features in nearly every browser came from Opera.
Okay... but you could always turn if off. I personally like having my 'status' things down there, things like gmail, lastpass, etc. I prefer to have the status items separated from the control-type items on top. I don't see why they had to nuke it.