The UI can be a little clumsy in a few places, though for the most part it's useful enough that I'm willing to overlook that. I'm definitely happy that as far as I can tell, tabs in a hidden container are maintained between sessions (assuming you have that option turned on) and can't be accidentally closed with the "close all other tabs" or "close all tabs to the right" buttons. On the other hand, tabs almost never reload properly from the "undo close tab" button, so if I do accidentally press the "close all tabs" button, everything is gone. It's extremely frustrating.