I prefer this one because I can access it anywhere and so actually use it more for studying, the charts are easier to understand and compiled for you.
I feel like this app really knows me! The personalization of content and score is amazing and I enjoy solving tough questions. The explanations are very good. Always accessible especially on flights when I don't have internet connection.
The app was very helpful with building my 1 minute internal clock ability. In addition, the solution explanations were very insightful. This app is a must for anyone studying for the GMAT.
This ap is an awesome way to carry GMAT preparation around. I use it during long waiting hours at Reception or site meetings.