It's looking a bit noisy, could use some work to clean up the stray pixels and jaggies.
Where is the light coming from? Each limb seems to be lit from the front, but each has a slightly different direction, and the head seems lit from the side. Frontal lighting in general tends to look very flat since it doesn't create any significant form shadows or cast shadows on the character, i.e. it doesn't show the character's 3D form.