If you like the work of H.P. Lovecraft, you might be interested in reading Kenneth Hite's Tour de Lovecraft, where he critiques a bunch of Lovecraft's stories, in chronological order. Read it from the bottom up.
With stories this good, I don't propose to spend quite as much effort dragging out their structure and such, or summarizing previous criticism. I can't help, however, joyously remarking on the deft way Lovecraft turns Poe's "House of Usher" inside out with this one. We get the same conceptual play on words, as Delapore descends simultaneously into the putrid bowels of his "house" (Exham Priory) and his "house" (the De la Poer lineage). Like Usher, Delapore's line is extinct -- his son dies of his WWI injuries. We get the same excitation of the sense of hearing as the symptom, almost the literal entry-way, for the horror. But unusually for Poe, "Usher" is not particularly fixated on Usher's interior psychological life, whereas equally unusually for Lovecraft, "Rats" is very much concerned with the interior life of Delapore. In this story, Lovecraft proves himself able to master Poe's tools and move on -- it serves as the solid foundation for his triumphant farewell to Poe, "Charles Dexter Ward."
In my own case, reading this story also let all the light in at once about the "house as violated human body" subtext that William Hope Hodgson used in House on the Borderland. Indeed, "The Rats in the Walls" is a great, if somewhat over-loud, haunted house story as well -- the comparisons with, say, The Shining just jump out at you.