There are many, many ways to study for these tests. Most of those ways offer exactly the same material as this way. This way is nice because it consolidates all of the tests into one app on my iPad and iPhone, beyond that it isn't anything special. However, ease of use and organization is quite nice.
Unfortunately, AviationExam fails to deliver. I've already listed its strong points so I'll list it's weak points.
Synchronization - takes an excessively long time (nearing an hour with a very high speed wifi connection), it also occasionally fails to save requiring you to synchronize more than once in a day.
Test Questions - Many figures do not work (you can uninstall, reinstall and re-synchronize which can take over an hour and may or may not work)
These are really the only weak points I've encountered, unfortunately they render AviationExam next to useless.
Fortunately these are things that AviationExam developers can almost certainly fix if they care to. Hopefully they do.