I took the
MGMAT course and I was glad I did. It helped me boost my score from the high 600's into the low 700's.
Having said that, I actually won the course so if I had paid out of my pocket, I probably would have been a little disappointed. Not a bash on
MGMAT by any means, but I already had some of the
MGMAT guides and there wasn't a great amount of new content in the course. The instructors were phenomenal though and considering I didn't pay a dime, it met my needs.
If you have all the
MGMAT guides and you're self-disciplined to study on your own then I would skip the
MGMAT course. I can't really speak to any courses from other companies, but I was disappointed with the Kaplan Premier book - it turned me off Kaplan.