how does this effect how the reader perceives the killer?

Poe liked his twisted killers. He selects an unstable killer who has delusions of grandeur. This fascinates the reader because he is so eccentric. We hear the killers voice and his passions unfold as the killer tells us exactly why he is such a criminal mastermind and how he shall perform his cunning murder. We also hear the increasing paranoia in his voice which is fun!