I would recommend Marty to anyone looking to improve their GMAT score and or to get comfortable with the GMAT.

Before taking the course, I scored a 570 on my first practice test. After the course, my GMAT score improved to a 700.

Marty's teaching style and personality made the course actually fun, if you can believe that. I became comfortable with the GMAT questions, and Marty's tips and tricks really helped me to improve my time spent on each question, especially math. Overall Marty made the whole experience easy and I was confident as I took the GMAT.

Thanks to Marty I got the score I was aiming for and will be attending the Ross school of Business this upcoming fall to pursue my MBA.

I took the 8 week class in the spring of 2012. My class had 5 students and the instructor was fine, but not good. He read straight out of the manual/Princeton Review GMAT books for 3 hours a week. We skimmed over every topic, without regard to the topics that would be most useful. Additionally, the VERY different skill sets of my classmates made it nearly impossible for the instructor to help the 2 of us who were shooting for a 700+ score (I also think the students at the bottom end of the curve were frustrated as they often fell behind or were confused, and the instructor was unable to help them.)

The online materials were weak at best. In particular, the online practice tests felt VERY different from the official GMAT practice tests and my scores were significantly lower on PR tests. It was disheartening and I almost didn't take the exam as I didn't want a sub-600 (!!) score on my record.

At the suggestion of a co-worker, I purchased the Manhattan GMAT practice tests and used those heavily for the month before the test. The scoring seemed MUCH closer to the GMAT practice tests and the format felt more like the format on the actual test day. I felt like I got more out of the 6 purchased practice tests than 8 weeks in the Princeton review course.

I would suggest not wasting your money on the Princeton Review course, especially if you want a very high score.

Having come into Princeton Review with no clue about the GMAT but for the usual version read online, it was great to end up with a score of 730 (Q 50 + V 39) along with a 6.0 in AWA.
A preliminary mock test gave me a score of 620 with Verbal at a meager score of 23. From here, thanks to the excellent guidance by Merrily and Vikram as well the good material provided by Princeton Review, this score rose up by 16 points!
When I chose to take up the GMAT course, I knew that Quant would be fairly simple and would be a breeze considering that my skills with Mathematics were quite good. This was not really the case as a knowledge of mathematics does not mean you can crack the GMAT. Very useful tips from Rohit helped me score 50 in Quant.
AWA saw the best improvement, by far. From writing essays that could get no more than 3, I received a perfect score of 6 on the GMAT. This would not have been possible without Vikram's extremely good guidance.
Overall, Princeton Review was a great experience for me, from the books to the faculty and I would definitely recommend the same for anyone who wants to crack the GMAT.

I initially enrolled at TPR with the idea that having someone to whom I was answerable - would make me more focused towards my GMAT preparation.
If I remember correctly, my diagnostic GMAT score was 550.
I thought hard work would be enough to get me past 700, but I was wrong.
Immense credit goes to the teachers at TPR who guided me and helped me with issues that were unique to my style. Their guidance was useful, not only for GMAT prep, but also for understanding the nuances of the application process.
I especially found the "booster sessions" provided, very useful as these helped me identify the flaws in my process of approaching and understanding questions.
But more than their technical inputs, the confidence and encouragement that my trainers infused me with helped a great deal.
I still remember my trainer saying that he was willing to pay for my 2nd attempt at the GMAT, after I scored 710 - saying that it was under representative of my abilities.
Their faith in my ability, and their nurturing of the same - is what made my experience with TPR truly memorable.
Really do owe TPR one for this!