What an odd story! As with a few before it, I didn't enjoy this one much when reading it, but the discussion in the episode really helped put a better perspective on it. In particular I really liked the framing of it as a plague story with the spectre of cholera hanging over everything (for some reason it hadn't occurred to me that the omen of death was an omen of them getting cholera), and the idea of it as a reaction to the science of the Enlightenment.
Thanks also for making the weird political digression make sense! It completely boggled my mind what it had to do with anything else in the story. I'm still not completely convinced, but I guess it worked for Poe.
Overall I thought this story had a lot of great set-up; the evocative description of the cholera epidemic and the tantalizing hints of the tomes in the library would make an excellent introduction to a different weird story. As it stands, though, the description of the beast and the revelation about it didn't do anything for me. Maybe that's a problem of perspective as a modern reader, which at least would fit with the theme of the story in a roundabout sort of way.
I also found the story a bit odd when first reading it, but I really like the style of almost all Poe tales, and that also applies to this one. The threat of doom, physical and mental is as gothic should be. Even after the 'solution', the moth, is given, the feeling of impending doom still remains (and also in the protagonist I think - his optical illusion of the monster still counts as an omen).
When the Decamarone was mentioned in the discussion, I also had to think of Worlds' End - volume 8 of the Sandman, in which people/creatures end up in a interdimensional cozy tavern and telling stories, while there is something grand happening to the worlds outside (the death of an incarnation of Dream).