I tried the demo for an hour or so and thought that it was v similar to the EZ Drummer / Superior Drummer MIDI files in that you could create something, but it would be unoriginal and quite restricted.
You're probably better off learning to play (I don't, but I know a lot of music theory).
Some plusses though, at least you can change the key or individual chord types in the VST (unlike the drummer MIDI files) and the piano (standard version) is very nice sounding. Nice interface too.
Another negative or so, the keys available are only Major and Minor. No Modes and no blues etc.
In short they need to extend the number of available keys, add modes, increase the number of MIDI files and improve how to find the bit of MIDI that you want / need.
Maybe V2 will be of more interest.
I still prefer Harmony Navigator, for songwriting.
What would Bob Clearmountain do?