Hello, creator here! I made Composer's Sketchpad as a sort of modern take on sheet music. My goal was to make the core loop of drawing, playing, and editing musical notes as tight and intuitive as possible. (You could say the app is aimed at making musical rough drafts.) Unlike most sequencers, notes can be drawn at any point in time and bent to any pitch, making the app very suitable for playing around with melodic solos and complex rhythms, as well as microtonal experimentation. (Notes can also be snapped to the time/pitch grid if you prefer.) Everything runs on MIDI under the hood (though unfortunately MIDI-in/out aren't currently available), and MIDI file export is coming in the next update. An iPhone version is also in the works.
Good Spirits
Zask