While I enjoyed the story, its base premise seems to be flawed.
"In a futuristic dystopian Chicago, society is divided into five factions: Abnegation the selfless, Amity the peaceful, Candor the honest, Dauntless the brave, and Erudite the intelligent. Members join a faction based on their choice but are given a suggestion by an aptitude test."
The test results of Tris, the heroine of the story, show attributes of several factions (Abnegation, Erudite and Dauntless), meaning she is Divergent. Tris spends most of the movie keeping this a secret, as Divergents are considered threats to the social order and are persecuted.
To mask that she is a Divergent, Tris's test results are recorded as Abnegation (the faction into which she was born). However, at a choosing ceremony, Tris joins the faction of Dauntless. She then proceeds to pass various stages of testing to complete her initiation into Dauntless.
At one point, Tris needs special training from her boy toy, the dark and stormy Four (stupid name) to complete her final initiation test as a Dauntless would, as making choices unlike those of Dauntless would reveal her to be Divergent to the powers that be. To me, this demonstrates a paradox.
If passing the Dauntless final test is facilitated by making choices as Dauntless would, then anyone who doesn't via assessment test match into Dauntless but chooses to join Dauntless and successfully passes initiation should (either be Divergent or) possess the qualities of more than one faction - that of the house they matched into and that of Dauntless.
I understand that according to the story, Divergence is a special quality, like a physiological condition, existing when a single individual possesses attributes of more than one faction - a big no-no for the government. But, if you're going to allow for choice, anyone who tests into one faction but joins another also possesses attributes of more than one faction - that of the house they tested into and that of the house they chose and successfully joined. The existence of choice begets its own kind of divergence.
I'm guessing the ultimate revelation could be that everyone is capable of divergence and that factions are simply a tyrannical system of control imposed upon the masses which when confronted will enable people to realize that they do not have to exclusively embody one defining attribute. In that case, choice should have been eliminated to keep the pre-revolutionary ruse intact. It's totally inconsistent to persecute Divergents if you're going to allow people to choose a faction despite what they test into, unless the expectation is that anyone who chooses a faction outside of their test results should definitely fail, but that doesn't seem to be the case in the story. You would think the Erudites would have figured this out already?
p.s. According to Wikipedia, the author of Divergent wrote the novel "while on winter break in her senior year and the movie rights sold before she graduated from college." I was lucky if I got through a load of laundry during my winter breaks.