PBL is the greatest thing known to man. Lecture, screw lecture. I fall asleep all the time (at HMS you can watch lecture over the internet, so I don't even go most of the time). As far as certain people hogging group time, that won't happen just because someone will tell him or her to shut the hell up. It is actually pretty interesting in how eight people can come together, talk through a case, and gain understanding to every aspect of the medicine of the case at hand.
But, then again that's my personal preference. You definately learn more clinical vignettes in pbl than lecture which is dry and straightforward, while pbl is active and has no real format. It's up to you and the group to get everything you can out of the case.