This has been my favorite Langan story, so of course I'm happy to see it here. I always liked how it combines real facts about the story and writer that inspired it with fictionalized stuff until one doesn't know which is which, kind of like Lovecraft's approach in that respect. It also starts out with a truly fine appreciation for Poe's sentence structure that rings true and is genuinely revealing of something about Poe's awareness of his craft and the way the original Masque story worked.
Even when I first read it, one could see the ending coming, but it's still pleasantly creepy in its presentation. All and all, a dream story for a literary horror fan.