The book isn't exactly a part of the Poe canon. There are parts which are boring as hell. Some of the bits are powerful. Everyone thinks the book stops in the middle of the action - maybe it was due to Poe's alcoholism or something like that. Poe constructs, however, a pretty thick theoretical (and also rather jokey) frame around the narrative that's supposedly written by the real Pym, and ending the book as it does must've been Poe's deliberate decision. Nevertheless, the ending with the scream "Tekeli-li!" is sure to get stuck in the reader's mind.
I found out that Poe got some inspiration from J.C. Symmes's theory of Hollow Earth that were circulating around the time Poe wrote his novel. It makes the ending even more powerful. No wonder that Jules Verne wrote a sequel to the novel, called The Antarctic Mystery. (Here's a pace of Poe-related fan fiction, there may be some stuff related to the Pym adventure.)
I wrote a review of the novel for the Kulttuurivihkot magazine. It will be out only in some months, so I thought it would be appropriate to already post it. It's here (in Finnish, of course). Note on the text: I didn't think that the translator Kapari had much evidence for her suggestion that the book might be autobiographical, but there seem to be others who think the same, and actually it seems it's a consensus on the book. I don't really see much relevance to the idea of reducing the book to Poe's life, and I can't quite gather how all this relates to the idea of the United States's identity, as some scholars seem to say. Maybe I should've gone to greater lengths about this.
(By the way, here's my earlier take on Poe's short stories.)