In addition to playing the built-in instruments, you can also use the aQWERTYon as a MIDI controller for any DAW or notation program. Just set the input to the IAC bus (Windows users will need to install MidiOX before this will work.)
The problem is many of us don’t really think that way. My personal musical goal right now is to play piano like Errol Garner. How the heck do you start on that journey? Well, it begins with a process of breaking things down into smaller and smaller steps until you wind up with something that can be realistically accomplished in a practice session (or a few).