This might get moved to the discussion boards so that you can have a variety of responses.
For me, "The Raven" is dark from the beginning. I know Poe, and knowing he is the author, I prepare for depression.
By the time the last stanza is upon the reader, there have been allusions to death, hell, and evil. The concept of nevermore has been repeated so much that it seems like something will be revealed that is final and complete. The references to the raven seem to demonstrate a relationship between Poe and the raven. This relationship seems strained and it is as if the raven knows Poe's spiritual and soulful pain. The poem is certainly seemingly over the lost Lenore, but more than that, I think this poem demonstrates a lost Poe. He does not know how to exist anymore since she is gone. The raven seems to understand his pain.
Therefore, the poem ends for me with depression. Pain does not feel good. This poem demonstrates emotional pain which depression certainly embodies.