I can't help but draw comparisons between Hannibal and Dexter. The latter is a charismatic killer who follows his own code of 'ethics' whereas Hannibal is more intimidating and seems almost chaotic. Dexter's targeting of criminals allows the viewer to justify rooting for him, but why would anyone want Hannibal to succeed?
What does that count for when the viewer knows he's a remorseless serial killer who, unlike Dexter, does not limit his actions by applying a code to them?