Best Value

I signed up for Magoosh early in my GMAT Studies. And since I hadn't taken the test before starting with Magoosh, I can't say how much it improved my score. I will say however that it was a huge help.

Pros: I hadn't thought about math since graduating years ago and Magoosh was a perfect refresher. Mike Mcgarry did a great job explaining concepts. They provide really great information throughout their blog. The amazing video explanations at the end of each question was the highlight of the course.

The Cons: It's really easy to spend too much time watching the videos and too little time doing actual problems. The Timer function on the Magoosh Practice tests counted up instead of down (like the actual GMAT does) so that was confusing.
There are a lot of GMAT tricks/techniques that I didn't think Magoosh covered as well as they could have. I would have liked to have seen better analytics in their dashboard.