depends on which school u go to. Most of the time is systems based ( background block, cardio block, renal block, neuro/psy block) where they throw physiology, pathology, anatomy, pharmacology and some bits of embryology at you all at one shot and u finish most block feeling somewhat incompetent and lost due to information overload. Some schools have separate final anatomy exams at the end of preclinical years.
PBL is useless. It's exciting initially as you all compete to bring interesting teaching, latest research into the PBL room, but after a while, PBL is a bother and u are better off studying yourself, esp when zealous classmates start to talk about optics, going into mathematical formulas worthy of a Phd in optometry when the learning objective is about about mypoia, or explaining the six different axis of psychiatry when it should be about mood disorders. I go to PBL typically for the food ( auzzie can really bake, some of them) and as a break from my own studying, plus some ooggling at the pretty pbl mate.
attrition rate is ZERO? They do try to let u pass in preclinical years if you can demonstrate a level of medical knowledge, but they will weed out unsafe guys during the clinical years. You can ace ur exams, but if the clinical evaluation comes back as "incompetent in patient management", " unsafe" etc, u will not get a pass.