ManhattanGMAT Review

I have found Manhattan GMAT's Complete Course (the 9 week course) to be one of a few truly fine products in the world. There is plenty of content and additional study material beyond the individual class sessions and homework assignments. If you are willing to commit the time (which is a lot) than there is no other prep program better than ManhattanGMAT. I could not recommend this program any more highly.

I also found that ManhattanGMAT's "Thursdays with Ron" to be particularly useful. I believe that this is a resource that only ManhattanGMAT has.
I scored a 620 on my initial diagnostic and ended up scoring a 720 on my first actual GMAT exam.