Cerberus, had to remind me about those Roman numeral questions, didn't ya?
I didn't take TPR (I took Kaplan) but I found the AAMC practice exams (particularly IIIR, IVR, VR, and VIR) to be adequate representations of the real thing.
I took the August MCAT and found the...
...Physical Science section to be the same difficulty as the physical science sections on the practice exams. I was expected to have a very basic understanding of physics and to have memorized a couple of dozen equations. There was a freaky, conceptual passage on exploding asteroids that beat the holy F out of me and my score. This was the most difficult section but not much different than what I had experienced with the practice exams.
...Verbal Science section to be a little easier than the verbal sections that appeared on practice exams... reasons being they took away five questions and provided passages a little less abstract and easier to understand. I can't speak for TPR, but Kaplan has good verbal strategies to use early on; however, their practice verbal materials s-s-sssssuck. The reasoning behind some of their answers is a tad different than the reasoning behind correct answers on the AAMC exams - stick with AAMC material, especially right before you take the real thing.
...Writing Sample to be... nobody wants to hear about this. Don't get a 'J'. Next.
...Biological Science section to be set up almost EXACTLY the way the practice bio sci scections were set up. Most of your answers come from the passages. You are not expected to recall iddy biddy details from your biology courses. I look at the bio sci section as an extension of verbal reasoning, only with graphs and long, hyphenated words. The O-Chem was basic. They took out most of the good stuff last April 🙂
All that being said, the AAMC material was VERY VERY helpful. Pay the 80 bucks, or whatever they're charging, make print outs of the exams, take them under time constraints, and use the internet tools to evaluate your answers... iz tha bomb. The Kaplan people (and perhaps TPR people) talked down the AAMC stuff, saying the MCAT writers wouldn't repeat the same questions and that they would try to trick you... about five or six problems on this passed August's exams were more or less taken from the practice exams. They may have changed the topic of the passages in which those questions appeared, but if I remember correctly, one such question used the same numbers on both the practice and the real thing.
A good coaching service like TRP or Kaplan will motivate you to study and review your basic science, but if you are looking for some material that approximates both the demand for knowledge and trickiness of the real thing... go with AAMC.
To answer your questions of how I felt leaving the test in August and how closely the AAMC pratice test scores approximate what you will earn:
I left the exam knowing how I scored in each section... I got my results and wasn't the least bit surprised. I think that's cuz I took every AAMC practice exam I could get my hands on and I developed this sort of sixth sense, where I could tell if I had gotten, say, a ten or an eleven on a section before scoring it... the practice score approximations are close to what you will get on the real thing, but don't smack your head against the wall if you score you don't like. Find out what you're doing wrong and see if you catch yourself doing it on the next practice exam... your score can improve like crazy once you see patterns.