There is a lot of background that only draws attention away from the subject. My eyes are immediately drawn to the purple flowers in the background and miss the subject entirely. Personally I would have cropped much tighter to eliminate all of that background clutter and let the subject stand alone.
As mentioned, the horizon is tilted.
While I realize that the way his head points isn't necessarily the way he is looking I would have put the lizard on the left side of the frame so that his head is pointed toward the center of the shot and not out of the frame.
Excellent focus and exposure, I just don't like the composition personally.