OK. Suggestions...

As is, limited in age range interest. Could increase enjoyment & age span if you added:
1. An eraser for older kids who want to improve their work-- or is that what the white paint is for? If so, its rather tedious to erase in pencil line thinness. You need something wider.
2. A playback for the finished painting. You know, either choose a left to right playback or "as drawn" so that it plays the sequence of the strokes as they were made.
3. Thick and thin strokes. Or, did I miss that?

Otherwise, its an ok app.

Daffodil girl about Musical Paint For Kids