Very good but not great.
This is a very very good app and well worth the money. I found it easy to remember the meanings of the kanji, if not the readings. There should be a quiz for that too!
Also, the multiple choice answers are just a random selection of other words/kanji from whatever level you are studying. It would be more helpful if the answers were similar sounding/looking, making it more challenging and difficult to guess. After all, that is how the questions will be presented in the actual JLPT exam.
Kbrookej about
JLPT Study, 1-5 Level Kanji and Vocabulary Japanese Language Proficiency, v2.5.3