Does not work as advertised, very unintuitive
I spent the money on this app in order to have a host for using the awesome AudioKit Synth One app as an audio unit extension in GarageBand (right now that app only works with inter-app audio). Ostensibly, this app offers that feature. In practice, opening this app as an audio unit extension in GarageBand offers very limited options including the app's own built in patches. As a stand-alone app you can use it as a midi controller for Synth One or other compatible apps, if you can figure out the labyrinthine, amazingly unintuitive interface with essentially no instructions. However, the keyboard interface harsh on the eyes and as basic as it gets. If there's a way to get it work as an audio unit extension with GarageBand I haven't figured it out (I've tried adjusting all of the nightmarishly convoluted settings and GB still doesn't pick up any audio output). I appreciate that this is likely an independent developer trying to build a useful product for musicians. If it were a free app, or if there was a free version or trial I would not be complaining. However, I'm sorry to say that this product as it stands presents a very frustrating user experience and simply does not work as described. Save your money.