I go to the same school as Instatewaiter, and I really cannot overstate what a worthless waste of time our implementation of PBL is. I would rather sit on the floor in an empty room doing nothing for six hours than be in TBL for two hours. However, we don't have that choice, because attendance is mandatory. I would avoid PBL like the plague. Granted, our version of it is particularly awful (we break into "small groups" with all 186 of us in the same lecture hall) but the whole idea is terrible.
I wish sometimes they would just grade us on how long we can keep our arms in buckets of ice water or something similar. Ultimately it would be more humane.