I admit that the premise is pretty silly. There's this purple monster that just comes out of nowhere. I still liked it. It's mostly because the animation and movements are nice. I especially like the scene where he dodges and it just shows rock going at the camera. I could feel some sympathy for this guy.
I think this should have been longer. Then again, it may have meant to be more like a short music video. The monster had nice mobility. The story seemed silly for its song. It does have good serious moments, though.