I took the Manhattan Prep 9 session course with Keith Blume in Chicago. I was very pleased with what I got out of it. Keith is a natural teacher, and his course sets out the path for what you need to do each week. If you commit to the course and put in the work, you will definitely end up better off. After completing this course, I walked into take the test feeling very confident and was able to beat my goal by over 20 points! Up 100 points from my very first practice test.
Anyone who is serious about doing well on the GMAT should look into this course!