Now on version 0.5, the latest release includes the following changes and improvements:
Fixed a typo sring to string which caused a crash in certain situation.
Modified logic, if word was not known immediately. Now it's not marked as known when you correct yourself.
Improved usability by adding new notes and changing option texts.
Added an option to switch the font color. I did some usability testing and they considered that it's difficult to see the answers if background and text are white (may be a problem with picture lists).
Added an option to wait a press after the right answer (requested by Kassad).
A possibility to search English definitions. For example, you may create your own phrase book for Japanese (or any other language) and use it when you're visiting the country. If you want to use pre-made sentences, I parsed Tatoeba sentences (from 04/03/2011; approx. 150,000 sentences) for you. (extra feature)