I really like this. The eyes give the feeling of a real wolf, the shadowing and textures are amazing. The details are just incredible! His anatomy is very spot-on, which is pretty rare from what I see. His colors are also nicely matched to real wolves. Also, I adore the slight pink/orange hint around the sun. It makes the time of day/night even more believable.
My only issues are how light the nose is, the whiskers facing different ways (someone else said both already I believe), and the light in the right bottom corner. I thought it was a lightning bug or will-o-the-wisp. If so, I would add a couple more. If not I would remove it.