I took The Princeton Review prep course last year (2002) and the April 2003 MCAT (32 PS 10, VR 11, BS 11). I had about a month to study and relied on their material. I believe all the material that could be asked on the MCAT was presented in the review material and in their workbooks. Of course you have to do all the passages, work the problems and learn from your mistakes.
A friend of mine is now taking a PR class, and this year's material looks even better than what I used, for example, each review now includes a glossary so when you have a simple/stupid question you can quickly look it up in the glossary (e.g. "what is a coulomb?") This would have been better than searching the text.
The real disadvantage of TPR is its cost, I believe an MCAT course costs $1300. But think about how much you have spent on classes in college. The money spent on a prep course has a much higher return.
I don't have much experience with the other test prep material so they may be suitable also. From my limited experience, everything on the MCAT was in metric scientific measurement, so any test material that uses English measures or has you solve conversions is out of touch with the content of the MCAT.
