I love the fact that the background is out of focus, which is further emphasized by the 'fuzzy' glow around the 'sroom'. The use of color is wonderful, you can never go wrong pairing green and red as they complement each other. The bright crisp colors and the addition of the mouth & tongue gives it a fun feel, which is very appropriate considering the origin of the 'character'.
Maybe it could have been placed better rather than centered, because it kind of feels flat. I think the face was supposed to be the focal point, but my eye goes straight to the white spot which feels centered on the head and is also very bright compared to the face. You could dull the color of the white or shift it so that the bright white spot no longer feels centered detracting attention away from the face.
I liked this piece for its bright crisp color and it's fun nature. It ties in with the game world because of it. There are just a few things that I feel that it needs in order to be an even better piece.