What are some alternatives?
When comparing Piano Notes Fun and MyMusicTeacher, you can also consider the following products
Yousician - An interactive guitar-learning app.
Simply Piano - Fast and fun way to learn piano
Melodics - Melodics is a desktop app that teaches you to play MIDI keyboards, pad controllers, and drums.
Flowkey - The easiest way to learn piano with your iPhone or iPad
Jameasy for Violin - Play rhythm game with a real violin. you can play with background music and real-time feedback
TuxGuitar - A Multitrack tablature editor and player.