Tapping the screen eliminates the benefit of using the cover alone as input and makes handheld use of this app even more difficult.

One might not be able to keep score easily with paper flashcards, but that doesn't mean it's not useful. I'm not that familiar with handheld flash card app space, but I could see an app providing score tracking and more frequent interweaving of previously missed answers, and an overview of immediate feedback can be helpful.