GarageBand on iPhone. Not as easy to use as on a MacBook but Amplitube iRig and MultitrackDAW seriously want to rethink their pricing! This top dog of “prosumer” Digital Audio Workstations (DAW) is killer at AU$5:50 on the App Store, yet pretty much does most of what it’s Macintosh sibling does, except mayby track counts and inputs.
Onscreen instruments are better suited to iPad, I think, but still quite usable 
for sketching a melody or bass line. The Automatic Instruments seem at first play to be a little “samey” but I think there’s a knack to how you you use them which will come with experience. It’s certainly better than having a favourite drum loop and using it over and over in the same song, though. (Guilty as charging myself…)
The interfaces for tracks are familiar, too. The effects are done in a typically iOS way, but make sense in a GarageBand way. There guitar amps (shown), effects pedals (shown), loops and recording tools are are all really nice simplifications for use on a smaller screen than your usual music DAW.
Like I say, familiar in evry way. Also, I’m told 4S has full USB classes, so I’ll be 
getting a camera adapter kit soon to try out my iMic, Singstars and GuitarLink. GarageBand for iPhone, worth every cent of its $5:49 price tag.
