Stunning!
I think this app is the one with best UI on the flashcards-app market right now. For me, a good flashcards app should have good organizing abilities (in terms of storing cards and reviewing them); good repitition system for learning to be effective; good results and tracking stats to keep the learners motivated; a good UI design to make the app more eye-catching (huge factor for anyone whose issues are with bad looking app). Great job nailing these factors. Hope the app got it support in the future. Looks really promising!