Im currently studying in Japan for a year as an exchange student. I mostly downloaded this app as a supplement to my other studies. Ive found it very useful! My two complaints are that there is no option to hide multiple choice (often i choose the right answer by guess or process of elimination) and that when studying kanji, it doesnt give the japanese pronunciation for the base word or words, just the extra examples.
Given that you can read hiragana and katakana, Id definitely recommend this app to anyone looking to beef up for an exam or just wants to flesh out their Japanese vocabulary.
Phloxxy about JLPT Study FREE, Kanji and Vocabulary Japanese Proficiency Level N5, v2.5.4