The jury is out with that one.

I belong to a very very large active music forum. Where most users run on straight pc or bootcamp for most of thier audio production due to the limitations of mac and the limitations of software, instruments, effects that can operate only in the pc realm.

When it comes to iOS there is a limit to two effects or instruments at a time and the navigation can be time consuming and frustrating to switch between instruments and settings. There are quite a number of libraries for mac however most only toy with them on the couch. It's not something they feel comfortable using on stage or in a studio.

Granted android has been sluggish with midi support. But musicians are somewhat budget concious and would rather put more money into other gear then an iphone. More over I find it's that usually "the boss" has an iphone so everything is dedicated to the iphone.