Not only is it a an excellent Music Box but also including an excellent sequencer where you can place notes out of grid if so desired.
It is now also very useful as a compositional tool as the latest update includes Midi export.
Something that can be useful for apps that have midi import but not the possibility to create swing etc by programming notes out of grid.
The coolest thing is that it is actually more than just a good music box / sequencer it is actually meant for creating physical paper strips to use in actual music boxes!
To read more about it go here:
Play Store link:
Music Box Composer