Possibly one of the toughest apps I've worked on. The hard part about this project was simply fitting everything in. Considering the app is actually 2-3 apps, the challenge lay in creating an experience that wasn't overwhelming to the user. It was important that each of the features were intuitive and easy to find. 
The project really put design thinking to the test, and was truly iterative, with dozens of variations being tested before reaching the point you see below.