I appreciate developer for such application.
The idea seems to be good but when I started using this app I found out that there are some small bugs.
I hope my comment will improve this free software. I can also help the developer in coding as I am a coder too.
some suggestions which can easily be adapted are:
User interface improvement for a better eye-catching interface
buttons are too wide and narrow. Iconic (square buttons with images) are too much better.
The app lacks a simple menu which is shown when user press menu key on the phone.
A font selector for displaying words would be nice:
with this feature user can select type,size and color of question and answer texts separately.
Bug (weak UI):
When one side of card text (question or answer) is too long, the buttons fall out of screen (below screen) so users can not turn the card or press "yes or no".