I asume this is the movie version since in the book he used a hammer.

I would for the colorsplash effect (one thing colour, everything else gray) keep the shirt and jacket grey instead of brown. That would improve the effect.

Other then that. It is not a bad picture.

I would myself have changed it so it looked towards you, made the angry teeth closed on each other and remove the middle part of the unibrow so they don't connect.

Also when I look at the scene from the movie. Jack still has more hair then this picture. So maybe add next time some hair extensions + he was not shaven.