A few problems to address

This is a great app probably the best music app on the AppStore. There is just a major problem with the sampling feature that should be addressed. So as you have it now it is nearly impossible to get samples to work together as they need to be the exact same key and tempo. You can change the pitch and tempo with the edit menu but there is no way to change the pitch without changing the tempo or vice versa. It is unnecessary complicated and can be fixed easily. Thank you for reading my suggestion I hope you consider implementing it.

Vhh44 about GarageBand, v2.2.1