If you are contemplating purchasing this app please know: IT IS VERY HELPFUL, EFFECTIVE, AND BENEFICIAL. I DEFINITELY RECOMMEND IT FOR LEARNING JAPANESE VOCABULARY.
Having said that, there are only two things that bother me:
1) Lexical category in each Definition:
This is basically the explaining of whether the term is a noun, particle, transitive verb, and/or etc. SOME definitions DO provide this information (which is AMAZING). However, there are also some that provide no way of knowing the difference between a noun,verb, etc.
2) Context
One of the best parts of some vocabulary is how it provides an example of the word/particle/etc. In the context of a complete sentence. However, this is only given in some. About a fourth of them provide no context, which can be confusing especially when the lexical category is not given. Context can mean the difference between "going to work" (as in going to the office) or "going to work" (as in going to participate in the action if working)
The app is SUPER helpful. It just needs to work a little on consistency.