The game is very fun to play, although I must admit that I didn't quite finish it, because I couldn't figure out level 20...
I think this game nails what puzzle/action games are!
On the technical side I had some complains about the camera movement not being fluid and I think that you could increase the over the top nature of monkey mode a bit. For example instead of (what looks like) the default particles, there are rocks flying around (or the enemies flying away instead of disappearing) and maybe a bit of screen shake to bring home the strength of monkey mode!
All in all very fun (until the moment that it feels impossible) and the monkey mode music slaps!