The shading around the head looks odd, and the shading on the head doesn't suit the rest of the body. The head seems flat, and pasted onto the rest of the body, and the unrealistic shadows behind it only reinforce my assumption.
I also think the head should be looking the other direction, because it just doesn't seem a part of the body; see how its body is facing down to the left? It looks as though you were originally having the head point that way, but then realised it would take away from the definition of the "d" so changed it. I suggest making the body curve more in the direction of the head, by turning his claws in that direction, changing the stance of its left foot (our left) and showing some kind of definiton caused by shoulder bones.
As for the tail, I think I see what you see wrong with it; it's too pointy? You should just try to make it rounder, and less like a needle.
