This app was not chosen as one of the best apps for 2014 by accident.
Graphics are OK, nothing special. But if you pass the long test prcoess in the beginning, you find a great UX across the board. Not to mention that the content itself is rich and interesting. These are all quizes that I actually did some back in High school (and hated), but with this app it's actually fun.
Anyone can learn at least a few good things from this app.