A lot of potential
This app is really good for what it is designed for, but it also has a lot of potential for things that could be added in as well. One thing that could be added as setting that could be activated are the notes that are the matching octaves on the strings, like if you press the 1st fret on the low E string, it would also show you where the note an octave higher or two was on the fretboard. Also, adding in the ability to see fingerings for certain major and minor chords (or others) could be implemented, depending on how easy or hard that could be to implement. Also, it's nowhere near as important, due to possible complexity of the programming, but adding in the ability to see what notes were on the higher frets like on the 15th or so could add to the experience.
