Great contrast between colours. You can really see the texture of the skin.
Some might comment on the noise in the background but personally I like it. It adds to the shot because of the texture of the lizards skin. A shot that immediately engages.
I really like your idea with this, but for advance editing rules, I think you could have pulled a lot much more color out of the chameleon. It seems a touch soft along the spikes on his underside and along the top of his head as well. Overall I'd say nice work though.
This is such a cool image. IMHO the background should have been tinted to match the green in his face and this would have been an easy 10 for this challenge.