Don't get excited yet. It does not work so hot. Here, I'll just paste the review I left on iTunes:
Could be fun, but needs work - 3 stars (ok)
I have a difficult time recording anything with this app since the drums are so glitchy. A slight wiggle of the phone will cause a drum trigger. It's way too sensitive- there should be a way for us to adjust that.
Even setting the dial to kick only or snare only - it's still near impossible to lay down a glitch-free track. The sample will cut itself off with SILENCE if a butterfly flaps his wings after your intended hit. A new hit should never cancel the prior. This happens over and over again until I eventually don't feel like using the app anymore. Perhaps a simple drum step squencer would be less maddening? The drum samples do sound good- if only I could record them without glitching.
The guitars also suffer from this same cutoff glitch. The mic hears some other miscellaneous noise (even though my mouth is right in front of the mic) and it just drops the previous sample. Not very fun when you are 8 bars in.
Yet another thing that blows: THE UNDO BUTTON IS RIGHT NEXT TO THE RECORD BUTTON. There will be times when you will destroy a recording that you just spent 20 minutes trying to make. NOT FUN. Why not more undos instead of just one?
The best way to use this app is to just use the "mic" setting and overlay your ideas with that. That seems to work fine with no glitches. The rest of the app needs some work. I really hope they do an update.