...
+ Succinct instructions for adjusting note length and pitch make otherwise hidden actions appear more obvious.
- No way to delete a recording.
- Not obvious to user how to switch from synthesized notes to actual recording of the user (if composition was created by recording).
Efficiency:
+ Large buttons with clear, non-ambiguous meanings.
+ "Home" button always remains in same location
- Editing while recording can be cumbersome to switch between actively recording and editing, and then back.
Safety:
+ No composition is "static" (it can always be edited later).
+ User can always leave the application and it will save the current state.
- No composition is "static". Perhaps a "lock" button can be instituted later.