Seems there is a lot of negativity towards PBL on this forum, but it also seems that school don't know how to do it and I get from comments that it's usually not "real" PBL but a scaled down version.
At my school we're entirely PBL (as well as organ based) and I like the way it's set up.
The problem given is only an excuse to fit in the stuff we have to learn. And there is more to learn or discuss than just what's in the problem.
I'll take neuro as an example.
Take the syllabus from your neuro class and split the content in 9 sections (e.g. motor patways, sensitive pathways, cerebelum, etc...). The problems for each section are gross descriptions of common deficit/pathologies.
First the group tries to explain the anatomy/physiology/pathology of the content of the problem. This is either very quick (when we're at the beginning of a unit and don't know squat) or moderatly long (1 hour tops) when we actually know some stuff.
Then we get a list of objectives (the material) which goes beyond the problem
(this includes: anatomy, physio, path, investigations, treatments, etc)
Then comes the biggest and best part: alone, you study the material covered in the section. You read, take notes, study, etc. This is exactly like "not going to lectures and learning stuff in books" (as so often read on this forum).
When the group meets again, this is what usually happens:
-we discuss the case in the problem
-go trough the objectives and we explain stuff (usually everyone speaks)
-there is always an MD present with the group. He validates the explanations given by students, give quick lectures on what's important or poorly understood, relates the material to real cases, and answers our questions.
A typical session lasts 3.5-4 hours and is split like this:
-discussion on the case in the problem (20-30minutes)
-objectives, questions and lectures from the teacher (2 to 2.5 hours)
-new problem (half to one hour)
In summary, PBL is learning by yourself and then validating what you learned with a group and a teacher. The "problem" is not really what is focused on the most. I understand that most school don't use PBL in this way. I gather that there is a case to be discussed as it would be in real life and an MD may be present or not. I agree that it's a waste of time in the first and second year.
Now i'll take a shot at the pros and cons according to my experience:
Pros
-no lectures (well, maybe 3-4 on harder topics and to review)
-you pretty much set your own schedule.
-it makes you keep up because you look like an idiot if you don't work between sessions.
-you can relate the material to a real case.
-you can assess the material you know and don't know (by reviewing the material with the group).
-you get a more intimate access to a teacher: you can ask as many questions as you want, get stuff explained to you, learn about real cases.
-you get to build on and reactivate knowledge as you progress.
Cons
-yes, gunners can show off (but the group and teacher usualy shuts them up real quick)
-if you actually like lectures, you're going to be miserable
-you have a relatively short amount of time to master a lot of material
-groups are changed every unit/organ so you could be stuck with a bad group for a while