The realism of the piece - the detailing in the clothes, Snape's and Harry lacking, the insistance of the flesh and blood Snape is bending to his whim/will - is more horrifying for being seen through a dreamy haze. The ambiguousness tortures - will Harry be a just doll, "real" only in Snape's (mad) eyes? Or is Severus a true necromancer?
And in a very personal note, the lack of nipples on Harry is deeply, deeply disconcerting. I just can't stop looking at this.