Reportedly, Jim Caldwell is a big proponent of the hurry-up. Also, Joe Flacco really likes, and feels most comfortable, in the hurry-up. And certainly, it has been very effective at times this year, However, there are some downsides. One, it is not a balanced offense. It stesses primarily short, quick passes, and uses the run basically to keep the defense honest. This tends to keep Vonta Leach off the field, and limits Rice's rushing touches.
Secondly, 3 and outs obviously use up very little clock. That is not a good thing for a defense that is old, banged up, and already has a tough time getting off the field.
I just hope that the Ravens do not become too pass happy. Joe is not Peyton. Rice has to get 20 - 25 touches per game. We have seen what happens when his offensive role is minimized.