JamExam have posted a rather nice review of the G2M on You Tube. It demonstrates a good range of MIDI sounds and shows what you can easily get with the G2M, and what fun you can have.
Check out the video here (and take a look at some of the other JamExam stuff while you're there):
http://www.youtube.com/user/JamExam#p/a/u/0/WLikw5SBqYM