Love the light hitting that eye...assume he was lying down here? Nice colour contrasts too. Check the sharpening halos (or are they compression artifacts?) around the whiskers...I know they are tough to represent nicely on a web-sized file
I like the tight look but feel moving the eye closer to a Rule of Thirds power point (Lower-Left Intersection) would strengthen. I tried it and with a crop from the right and bottom you can get close w/o clipping the chin.