1) I like the full screen format of the application. It really lends to memorizing words without distraction.

2) I like the way you've implemented multiple choice rather that a "flash card" approach.

that being said, i've seen several apps like this. the most prominent in my memory is http://quizlet.com which has more than one way of memorizing list, classrooms groups, and the ability to create your own lists. and it's free. that's tough to compete with.