Of all the portrayals I've seen of Jon Snow, this is by far the most moving and accurate. The first thing that struck me is the blending Ghost with Jon's furs, making them one in the same. It reads on so many levels if you understand how deep the bond between Ghost and Jon really goes. Two beings, one skin. The detail in Jon's face is perfect, he looks weathered by his trials but retains his youth as well. And the sorrow in his eyes, the forlorn that follows Jon throughout his life and only grows with time rings so true and clear here. Despite that, his strength has not been lost in the representation in any way.
Beyond the subject matter the technique strikes me as nearly flawless. Not a single misplaced stroke, nothing put to canvas without thought yet the cerebral way in which it was clearly created does nothing to mitigate the natural, organic feel of the piece. The only thing I would change, and it's minor, would be to make Ghost's eye a pale shade of red amidst the whites and blacks and grays. Nothing too powerful as to draw your eye away from Jon's face initially, but it would add just a needed touch of fury and for us die-hards, accuracy.
This is a masterful piece, the best I've seen of any of Martin's characters. "Well done" does not do it justice.