I might be addicted...
I never cared for Assault, much too one sided if your have a decent group of Ts. However when 24/7 Office empties at 11PM Assault is still packed (and seems to remain that way continuously) so I have been moving on over there lately.
I actually prefer playing as a CT on Assault. Unlike Office, the CTs are expected to lose every round. It's really a challenge to win a series on CT (and so far after two weeks I haven't seen it happen yet). I have been on winning streaks at a CT where the T's get restless and we sweep in and pillage them for 3-4 rounds but after that they get the idea and "dig in" again effectively stopping our run.
Anyway.. Assault, woot!