Well he made a conscious decision to not make him a cardboard cutout, his exact quote was "I wanted him to be really, deeply evil, not an idea of evil", and in order to do that, there does have to be some semblance, however small, of humanity. I think he's fantastic, he never pushes it over the top. I saw some scenes they were shooting from the graveyard when he's been reborn, and in one particular take, he was looking at his hands and crying out in ecstasy, which I didn't think would have worked, because it's not what he did in the book. We can see the monster that he is, but we can tell it's still a "person", not just some guy with digitized makeup.