The only thing that is keeping me on Chrome is buttery-smooth gestures (swipe left / right to go to previous / next page) on a MBP touchpad. If they have that built in I'd probably switch.
Also, Chrome has proper two finger pinch zooming on touchscreens. Firefox just simulates ctrl+scroll wheel, which is 1. slow and 2. not nearly as useful for the user. But that's not something I use often, I gladly switched over to Firefox again, this new version is really something.
