Very nice. Works well, but the coloration kind of make it look like it's some sort of construction droid/mech thingy. Might want to put more of an aggressive looking color to it if it's supposed to be some sort of killer.
I agree w/ you may be happier w/ different colors. These are veeery neutral.
Also, beyond just having different color zones, you may want to add some design to the body. Camo, racing stripes, that kinda thing. This is like an arena fighter right? Try giving him some more flash and personality.
The overall drawing and design are fully legit tho, as usual.