I love this app for guitar. You need an iRig or other iPhone interface to use it properly, though with AudioBus or IAA you can route audio internally. Once plugged in, you can zone out for hours making wild ambient sounds and hypnotic delay effects. It's very unique in that each of the 4 delayed sounds can be pitch shifted. Play one note, hear another back. And it's polyphonic, so chords are pitch-shifted too. Setting the delay to zero gives you a harmonizer. No intelligent harmony though. Wonder if that's possible in a future update? Anyway, I think my favorite feature is the Loop function in the master delay, where changing the tempo or delay time gives you wild, analog delay effects. Really amazing possibilities for creative expression. And now it is Audiobus and IAA compatible. Sweet!