I wouldn't recommend the iPhone MCAT apps. I spend a lot of time on trains, i.e. downtime, so I thought the apps would be a good way to get some extra studying in. I bought the iStudy apps for physics, chem, and bio ($2.99 each, i thinKi) and was seriously disappointed.
Not only did the apps have a limited number of questions, but I immediately encountered several mistakes. These apps must have been made by people with no background in the material.
You're better off making flashcards to use anytime you would be using your phone to study.