For a paid app, this product is quite limited. The depends on the individual to self-check their note recognition ... View (and hear) the note displayed on the screen, say (or think to yourself) what that note is, and then check the answer. Since you're not choosing from a range of possible answers, the app has no idea if you correctly identified the note or not.
This means there aren't any progress checks, or timed quizzes to see if you're getting faster or more accurate in your note recognition.
And, although there are three levels of difficulty (2, 4, or 6 octaves), there's no way to name a specific note range that you need to work on. So, once you select the 6-octave level of difficulty, for instance, the app still randomly selects notes from the 2- and 4-octave difficulty levels, which makes it impossible to focus on new material.
Bottom line, this app is light on educational value and heavy on price for what's offered.
Don't bother.