Veronica Roth's Divergent is not great literature. It is, as plenty of others have pointed out, a derivative revamp of the Hunger Games, which was itself a derivative revamp of any number of other future dystopias from 1984 to Battle Royale. Unsurprisingly given the inspiration thrice removed, "the book’s characters and themes are," as Michelle Dean put it in the New York Times, "blunt, coarse things, with almost no nuance."
The movie version is no improvement. Even Shailene Woodley’s considerable charm as the protagonist, Tris, can't entirely distract from the fact that the dystopian future seems to have been assembled by a video-game designer in a hurry, or that the plot is less a plot than a series of arbitrary challenges, many of which are actually ranked on a scoreboard. Tris undergoes a test/simulation to see which personality-based tribe best suits her (Erudite, Amity, Abnegation, Dauntless, Candor). Tris chooses Dauntless and faces a series of staged fights and trials to see if she's good enough to remain. Tris experiences more hallucination/simulations in which she must combat her fears. And so on.
The internal hallucination tests and the "real" adventures blur together more or less indifferently; they're just pasteboard hoops to jump through on the way to the uplifiting alternaballad at the end. All the mind-controlled drones at the denouement seem like a self-parody of the actors themselves, who point their guns here and leap off buildings there, not because they seem to want to but rather because the plot commands them to do so.
The lack of verisimilitude does not make for a good movie in the conventional sense. But at the same time, the film is more interesting than the average bad movie precisely because it so gratuitously, and even thematically, fails to fit together. Divergent, film and book, is actually in no small part about its own fakeness.
That's because its pastiche of sources includes, not just the Hunger Games, but the lurching grandfather of Hollywood sci fi, Philip K. Dick. Dick actually has a novel Clans of the Alphane Moon, in which a society is separated into tribes on the basis of personality types/mental disorders. But more than any particular idea, it's Dick's general approach to world-building that (whether first- or fifth-hand) seems to inspire Roth's novels. Where writers like Tolkien and Le Guin carefully constructed universes with every detail lovingly in place, Dick wrote as fast as he could type, deliberately creating fantasies that collapsed into discontinuity—fake worlds that acknowledged their own falsity. In Ubik, the default futuristic sci-fi setting begins to degenerate and fall backwards in time with little explanation; in The Three Stigmate of Palmer Eldritch, drug-induced alternate realities blur into "real" reality and everyone starts to turn into an evil cyborg demiurge. The novels crumble apart when you look at them closely.
A bastardized, pop version of Dick's sci-fi-with-holes blueprint has become one of the main resources of filmed sci-fi, whether in adaptations like Blade Runner or in knock-offs like The Matrix or Source Code. Divergent is very much in that tradition as well. That's especially the case in the series’ later books, where retroactive revelations are piled upon retroactive relations. But you can see Philip K. Dick in just the first film as well.
The basic information about how the world is set up—everyone tests into a particular tribe based on their personality—is revealed as false barely 10 minutes into the film. From there, the reversals mount and mount. The rules for passing the Dauntless tests are in flux, so much so that it seems like they're being made up on the spot; Tris is failed and then just allowed back into Dauntless for no particular reason; Tris's mother turns out to be entirely different than we thought. When Tris, in the middle of a fear simulation, suddenly realizes, "It's not real," she might as well be earnestly shaking the audience by the shoulder. When the fake water is rising in the fake chamber, and she taps the fake glass to escape, she might as well be cracking the fourth wall. This is simply a poorly designed hallucination, folks; turn the lights on and let yourselves out.
The plot gaps in Dick's world worked as a kind of metaphysical metaphor—the truth of the fictional fiction making the reader question whether truth in reality might be false, or false true. Divergent's goals aren't quite so high-minded. Rather, its piecemeal construction seems to be a way of encouraging audience identification, or even collaboration. Tris's main power is an ability to manipulate the simulations while she's inside them—to recognize that the story is a story and to write her own end. Since Veronica Roth is basically writing Hunger Games fan fiction, the analogy between character and author is obvious. But it's also an analogy between Tris and the reader/viewer, who plunges into a book/film/simulation, but can remain her or himself, reworking the story.
I wouldn't say that this is exactly intentional on Roth's part—but the novel's themes of discovering your true self, Tris's ability to write her own story in simulation, and the Philip K. Dick-style artificiality of the world all add up to a fiction where the author, reader, and protagonist spend a lot of time imagining and reimagining. Young-adult fiction at this point in its ascent is not just about books, but about film deals, fan discussions, and fan fiction, and Divergent seems unusually aware of these possibilities, incorporating them into its plot and themes as a series of metafictional nudges. Those nudges, at least for me, were part of the appeal of both book and film. Divergent's flaws invite you in. If it's poorly constructed, it’s because it is encouraging you, like Tris, to imagine something better.