Definitely too highly saturated. My eyes feel like they're going to bleed. lol
The other major problem with your colors is that your color ramp is directly toward white and black. You need some hue shifts to make it look less flat and more interesting. There's no indication of sunlight or shadow/backlight/ambient-lighting in your image at all. The brightest colors closest to the light source should all tend toward yellow (assuming it's a sunny day), or whatever the color of the main light source, and the shadows should tend toward blue (or whatever color of the ambient/reflected light).
Aside from the color, your image just doesn't read well -- his face looks like a blob of colors with no clear direction, so it makes it very difficult to tell what his features are or where they even are since there's just no contrast between them value-wise. I think if you add some darker shading to outline his mouth (by shifting the light source to, say, above and in front of the character) the face would be easier to read due to the downward-cast shadows. As it is, if you flip the guy horizontally, the light source would look really weird since it's apparently biased to the right side of the image.
The last critique I can really make atm is that his silhouette just doesn't read very clear. As in, his face doesn't give any indication of a nose/mouth if you were to change all the color of the character to a single black color. The same goes with his body language, since you wouldn't have a clue what that thing sticking out above his stomach was (his left arm of course, though at first glance, it doesn't appear to be adding anything to the image -- it'd be better to just hide it behind his body if you're going for a slouch sort of position)
Despite the harsh critique, you've got an interesting character idea at least.
