Very poor.

Im certain many people who try this app will agree with me when I say that Id rather carry around a notebook and and hand-draw staves than try to notate with this app. Its just unbelievable tedious to add notes, and its nearly impossible to get them in the right place. Overall, its not worth using. At least not yet.

For people who want to tough it out but dont want to upgrade in order to be able to save files: Im assuming taking screen shots (home button + power button at the same time) of your project will help somewhat. At least you wont completely lose your idea this way.

Rogert Theist about Music Drawing Notation