so for PBL based schools, it really depends on whether you learn best in a lecture-based setting, or a small group setting. Lecture based schools are exemplified by schools like P&S and UCSD, whereas, Cornell and Northwestern are known for their more progressive curricula.
Characteristics of PBL...done well
They'll give you specific case studies. For example, they'll say that a patient comes in with chest pains, high bp, etc. Then you work together to try to find out what the problem is, order tests, etc...through it all, a lot of time is used to research the physiology, biochemistry, genetics, etc. of the disease...this is all guided and facilitated by the instructor and the handouts...
Strengths of PBL:
Small group learning, led by 1/2 instructors - get to know students/faculty in a small group setting
Active learning
Incorporates group learning because each member is responsible for a discreet body of knowledge
Clinically relevant
Shortfalls of PBL:
A lot of people don't like PBL because they think it's a waste of their time. Whereas you're responsible for a clearly defined set of information in lectures, PBL can often lead to tangents and cause you to research information that you feel is irrelevant, i.e. lack of direction arguement. If you are a gunner/loner, you probably won't like PBL.