apple
FL Studio Coming to iOS
It comes with a 128-track sequencer, step sequencer for individual MIDI clips, drum loops, reverb, delay, equalizer, amp, and filter effects, all of this in one app, not to mention when you transfer your creations back to the computer you have the option of mixing it down to a WAV file, exported to MIDI or you can just import the session into the computer version of FL Studio.
It looks like the music creation app market just got a bit more competitive, look out Garage Band!