I'm a first year at SC' so my opinion is going to differ greatly from Typodont's, but I do understand/know about every single problem at USC. The way things are going right now here, the class of 2012 should be in good shape. The class of 2008 is probably screwed based on the fact that the things that are about to change here will probably not happen until mid spring to summer.
My opinion: I really enjoy the PBL process, especially the small group interaction and active learning that is achieved through this process. I've learned a lot via this process. I'm glad that they've integrated a Dental Anatomy course in addition to dental anatomy lab, gross anatomy course at the medical school, amalgam and composite courses as well as a Local Anesthesia course taught by Dr. Malamed (world renowned dental anesthesiologist).
If you ask upperclassmen, who have unfortunately had to deal with USC at its worst, they will express great resentment toward this institution. However, I genuinely feel that USC will only be getting better in the very near future.
Also, to clarify one thing on SDN, the dismal graduation rates of the past few years are NOT because of PBL. These low graduation rates are almost solely related to clinical issues and the administration, but from what I know, this will most likely be changing in the next 6-9 months.