Nice app + suggestion

I really like this app and it is indeed handy and useful. Pretty easy to use for anyone.

Although I think you should add a "Choir"/"Vocal" instrument too as the ones in the sampler do not fit any needs (literally).
Also the sampler is very hard to use as when changing the pitch the tempo changes too. Maybe adding an option where you can divide the options of changing pitch and tempo instead of changing the tone itself.

Mohi-M about GarageBand