Brilliant Design
I just love that it tracks questions you've 'mastered' and brings them up less frequently. And I really enjoy getting to guess again when I miss on my first answer - that way I can work through it and better understand the right answer, meaning I'll likely retain it better, longer. The profiles are a nice touch, too, so that my friends who are much better in German than I won't skew my training if they want to try the app. Plus, the app just looks great. I look forward to buying the additional 200 questions once I've got the first 50 down!