Looks really great. You've done a good job with the lighting and the contrast.
One thing I think that can improve your pixels further would be smoothing out your lines. Your lines are clean but they could be smoothed to create a better effect.

Mine is the one on the right. I have smoothed the lines out on the knee and the back.
The lines are smoother and look better even without AA because there is a transition between the length of the lines. It's hard to explain so try putting the image onto paint and zooming in.

Here is an example of a curve. See how the lines go 3px -> 2px -> 1px? That's the transition.
It doesn't make the biggest difference but I think you're skillful enough to start paying attention to the smaller details.
Keep it up.

EDIT: This doesn't just apply to outlines, but shading as well. Evenly distributed shades will look smoother than less controlled shadows.