A very nice job was done on the fur, giving texture to this cat. The small details, like the tooth and the freckles on the muzzle, add a lot to this picture.

Even though I see this animal as a cat, the head doesn't seem quite cat-like. The reason is because it looks like a lot of mass is in the muzzle, while the forehead is small. I suggest that it should be reversed when you draw your next head, putting more room into the forehead and sloping the face toward the muzzle. Along with that, the ears and eyes may need to be farther apart. Maybe add some whiskers too.

While I understand this is a headshot, the position of the eyes is confusing, as I don't see what he's looking at. Is he checking out its tuft of hair, or rolling his eyes? Consider the reason why your character would have a certain expression, and convey it.

Speaking of hair, I feel his hair tuft is off-center. It looks like it's coming out of his left ear. Since his head is turned at a three-quarters angle, the center of his head is shifted more toward his right ear, thus the hair needs to be shifter over too.

Overall it's a cute piece, and I hope you benefit from this critique!