This is BY FAR better than for example Sonic Mood, which has been sold here recently on MacUpdate. I was disappointed from its poor audio/harmony quality and cheap MIDI sounds.
1. It is free!
2. Even when you simply switch it on, it sounds better than certain shareware solutions!
3. Seems to have tons of options, I am just diving in!
Only minor issue - it is a huge download with almost 300 MB, but then again, the sounds have to come from somewhere ;)
So far I like the app a lot. Only complaint is a not very intuitive interface and non-standard look.