I would rate your app 4 to 5 stars.
This is because:
Pros
1. I have complete freedom over instruments, what they consist of (excludes percussion), and also a few colours.
2. Free Play. Jam to your favorite instrument. Extremely useful for chord practicing.
3. Unlock straightaway with your own key. This is something I like, because when I've lost it, I can retrieve and re-unlock the game again! Plus going portable makes it convenient for car rides, ships, and planes.
Cons:
Lags badly. Needs more work on the Video Creator, which must be ported to android.
Quits when playing too many instruments in Colours and Instruments.
Melody practice dots are too small on Android, and the keyboard keys are prone to making you do a mistake.
Android: Your app is brilliant!
No explicit, hateful, or hurtful language. Nothing illegal.