On the first TPR verbal I got an 8, and as an English major I was shocked and appalled. On the real thing I got a 13, and I hadn't "studied" for it in between time (well...other than what was required from my English classes). Hope that makes you feel better.
After reading over their answers I still stand that my answers are better for the most part. I dont think this test was at all like the aamc exams. I am somewhat afraid to take anymore non-aamc verbal exams now since they seem to look for different answers.
The Verbal workbook by TPR is very similar to the real thing. I think it has a bunch of practice passages followed by 4 verbal section tests in the back. TPR is by far the best test prep company (with the exception of Exam Krackers...they only offer classes in the East coast from what I've heard, but the books are awesome).
I think the TPR verbal is significantly different from the actual MCAT. In general TPR has much more of those "read and search for answer" type questions. The real thing is based much more on understanding of the passage and conceptual ideas. For what it's worth I scored 10-11 on most TPR verbal sections and 12 on the 4/03 MCAT.