Saw the movie when it came out, just now catching up to the novel--so it's difficult to avoid thinking of this as a fin de siecle mixer for Son of Spartacus, Wayne Gale, the second-to-last kid who played Spiderman, the girl from Dawson's Creek, John Boy, the cop from Fargo, the boss from Men in Black, and Wash from Firefly.
Lotsa fun, for what it is, which is an academic's apologia for writing novels while admitting in novel form the impossibility of the novel. (That the 2000+ page unpublishable unfinishable unreadable manuscript around which the narrative centers is autobiographical for Chabon should not influence our reading very far.)
Many lovely turns of phrase and fantastic details. The whole thing likely fits tangentially in some kind of pseudo-weird subgenre of fantasy, with all of the references to fictional Lovecraft imitator August van Zorn.
Probably a must-read for aspiring writers, with all of its commentary on the writing process, the life of writerliness, and so on. I found all of this to be non-pretentious, to the extent it's not simply overt mockery of aspiring writers.