beautiful use of dithering, AA, and lights/darks. Goodluck.

Thanks.  I almost chose a different background color, but seeing as how the area is so small I decided to recycle a color.

 Excellent dithering. ^^ 

 This is very well done; a clever take on the challenge that ends up looking pretty natural. I like how you used dithering to create facial hair texturing.

Great! Just loving this all the way!

 congrats, fair cropping given the contest, and a really good shape and outline, simple and strong. I would have chosen a completely different bg colour, but that's fine.

Fair enough.  And yeah, my understanding of anatomy is more intuitive than anything else, to put it softly.

I definitely considered that, and I also wish part of the bottom lip was showing.  The way I cropped it, I basically zoomed into it in my mind to make his hair fit the solid piece.  Any changes to the zoom or position would mess with the black part.  And I considered something like in your edit, but I'd be sawing his skull off, anatomically. 

And, the reference, as requested.  But thank you for taking the time to comment and make an edit.  I appreciate it.

This is very well-done.  I can't decide if I like the way you cropped it or not.  More specifically, I think I'm bothered by where you cropped along the bottom.  I wish that a little bit of the lower lip was visible.  However, even ifyou agreed with me and wanted to incorporate that into your piece, I understand it might be difficult to do that without messing up with the challenge.

I don't know if you'll agree with this either, but I don't really like the way the black goes all the way up to both corners.  I feel like the piece goes from looking well-developed to looking flat.  I think something subtle like this might help to maintain the illusion of form near the top of the piece

please don't take offense to what I've done to your work. : )

edit: oh, and I'd love to see the reference if possible.