Spooky sounds, even spookier themes, and lots of fun rhymes.
When the poem you are reading features death (especially deceased women), an elaborate rhyme, and mournful language, you can be pretty sure you're dealing with Poe. He loved to tell stories about depressed men, many of them pining for the women who have abandoned them by dying.
Poe was also very, very meticulous about arranging his poems for a certain effect on the reader. This effect was usually depression. Starting to notice a theme here? In particular, Poe felt that certain words could have an emotive effect on you: they would call up a particular set of feelings. One of the words used in this poem is "Nevermore." It's filled with longing and despair, a sense that nothing will get better, no matter how badly you – the reader – want it to. Combine the feeling of being completely depressed with hypnotic rhythm and rhyme, and you've got the essence of Poe.