MGMAT improved my score by 40 crucial points.

With no previous experience in studying for the GMAT, I decided to take Manhattan's 9-week online course. I found the class sessions to be somewhat helpful, the self-study materials to be more helpful, and the practice CAT exams to be most helpful.

Prior to the course (or any preparation)- my first practice exam - February 2012 - I scored a 720 (95% Verbal, 81% Quant)

By my third practice exam - March 2012 - I scored a 740.

By my fifth practice exam (on mba.com) - April 2012 - I scored a 750.

On test day - April 2012 - I scored a 760 (99% Verbal, 85% Quant

In addition to the 3-hour weekly course, I probably averaged about 8-10 hours per week (+4 more hours whenever I took a practice CAT). About three months elapsed between my first look at any GMAT materials and my test-day, so FAST IMPROVEMENT IS POSSIBLE.

I found some of the math materials to be helpful in teaching shortcuts that are useful for common problems (Prime Trees, Probabilities, etc).

I believe that it is easiest for a course to improve one's sentence correction skills, as this is the most objective verbal category. And Manhattan definitely succeeded here. My improved speed and accuracy in sentence correction accounted for much of my improved score, and I owe this entirely to the MGMAT materials.

Finally - the CAT exams. I believe MGMAT's CATs are a very accurate portrayal of the real exam, and the ability to review incorrect (and correct) answers was very useful in understanding my weaknesses. It was not until the 5th exam that the CAT question bank had exhausted 700-level questions. This is better than most (all?) other GMAT preparation services.

In short - I would definitely recommend Manhattan. I found the materials to be extensive, the program to be customizable to my own needs, and the practice exams to be better than the competition's. If you can afford Manhattan's class, you won't be disappointed.