I got my target score of 720+ thanks to Manhattan Prep, and highly recommend the MP program to anyone who is seriously considering applying to a top b-school. I say this for a few reasons:
1) The resources and course content are unparalleled, and very well structured. You start the process by taking a practice test that immediately pin-points your strengths vs areas that may need improvement, and then track your progress by taking more exams throughout the course.
2) The content is carefully curated, and is structured in a way that makes the classes effective without being overwhelming. The MP problem sets enable you to absorb content in the most efficient way.
3) The online interface is well designed and easy to use. Whenever I saw other interfaces friends were using, I was always thankful I decided on MP.
4) The instructor that I had (David Mahler) was amazing. He was intelligent, personable, always prepared, and a great teacher. He was diligent in answering emails, and always made himself available to students.
5) On top of the classes, Manhattan Prep offered a ton of events with top MBA programs which really helps when you get to the application stage.