First of all, I love the angle! It has the feeling of him coming to me, begging for help.. Or grinning in pain mixed with hate.

The hair is very well done, I myself suck doing hair (takes too long and I'm lazy). The scar in the face is also nicely worked up.

The eyes then again lack the depth. Don't be afraid to pull colors and use darker values! Same goes to the clothing and teeth, somehow it looks like it's still work in progress. The part just under the face should be in shadow, judging from the direction of light, unless the face is floating.

As for the hands, they're awesome. I envy anyone who can do hand well. Another part I'm not good at. You could've used a bit sharper values for them, but I think it matches the other parts well as they are now.

So all in all, very great work, even if it could have more depth in colour. Don't hesitate making absurd changes in colors