I didn't go in prep for the mcat but be forewarned that they only let you participate in that "track" if you are taking teh august mcat. I would not use it as my only preparation...
I attended the summer program, I went through the MCAT prep. What I gained from it was the numerous practice mcat problems we did. So I don't think it should be the sole preparation for the MCAT, it definitely helps to do some doing on your own before the program start in the summer.