Good

Learning the fretboard is very difficult. This helps, but I can think of one improvement. Currently, the moment you touch your answer to indicate your note guess, the question-mark-circle location on the fretboard disappears, replaced with a "correct" or "incorrect" notice. It would be strongly beneficial if the location circle would remain in view for a few seconds to allow the brain to absorb the association between the correct note and its location on the fretboard.

Asamaxmom about Fretuoso