Borne is a post-apocalyptic novel about a scavenger named Rachel who finds a strange pod nestled in the fur of the giant, flying, mutant bear named Mord who terrorizes the ruined city in which she lives. The pod is Borne, an organism that grows wildly, changes mercurially, adapts precisely, and forms an emotional bond with Rachel amid a backdrop of the ominous biotech-meddling Company, the rogue Magician and her roving bands of horrifically altered children, and her hiding-something lover Wick.
Borne ambiguously straddles the lines dividing apocalypse fiction, sci-fi, and fantasy. The novel never fully explains itself or resolves all the questions posed by its world building, which is ultimately one of the novel's greatest strengths. Critics have tended to name the fantastical ambivalence of the book as a tendency toward "fairy tale," but I see as essentially absurdist in quality instead; to my mind the admixture of elements that could be taken as silly (a massive flying bear!) with elements either richly emotional (Rachel's role in nurturing Borne) or grotty (the hardscrabble existence in a world riven by a man-made ecological catastrophe) feels more Max Ernst than Hans Christian Andersen.
I've yet to read a novel by VanderMeer that wasn't strongly constructed, imaginative, lyrical, and inventive, and Borne is no different. Nevertheless, despite how good the novel is, I'm confused by the critical lauding the book has gotten--not because it doesn't deserve it (it does) but rather because the reviews often evidence a real ignorance of how many great "weird fiction" books are out there. Take, for example, this starred review from Publisher's Weekly: "What’s even more remarkable is the reservoirs of feeling that VanderMeer is able to tap into throughout Rachel and Wick’s postapocalyptic journey into the Company’s warped ruins, resulting in something more than just weird fiction: weird literature."
Is Borne the first of its kind to ascend to the vaulted plane of "literature"? No. It's funny, the claim made by the Publisher's Weekly reviewer is meant as a compliment, but it does a disservice to VanderMeer's work in toto. He's been opening the door to the "literary weird" for quite a while. If Borne was your entry point, and you like what VanderMeer does in the novel, consider checking out Annihilation or a book in his Ambergris series. Alternately, you might want to look at a couple anthologies he's edited with Ann VanderMeer, such as The Weird or The New Weird, either of which may open your eyes as to the variety, depth, and quality "the weird" has always possessed.