Specifically, Matt Zoller Seitz review on Roger Ebert's web page desperately wants the movie to be about toxic masculinity and gender roles, and while that certainly plays [a/one of many] part(s), it's stupidly blinkered and ignores something fairly clear in the film's conclusion:
Ava is a sociopath.
Now to be clear, Nathan, her creator, is a monster. But he's ultimately a very common kind of monster: the kind who willfully ignores the implications and reprecusions of his actions in order to continue with the existence and work in which he is comfortable. Do his attempts to create an artificial partner who is "intelligent" and feminine but also docile suggest a pathological break from humanity? Perhaps- as does the isolation which clearly defines his existence. But he has clearly created a mental boundary in which even as he tries to make his creations more human, he can think of them as products, capable of being deleted and revised. He's oddly unique: a serial killer who never realized that was what he had become, because the self-awareness of his victims evolved over time.
But despite Ava's desperate communication that Nathan is lying to Caleb, Nathan is fairly honest with Caleb, and on one point in particular, devestatingly so: that Ava may be faking her affection for Caleb toward her own ends.
She is, in fact. Which is something that the ending makes penetratingly clear: she not only leaves the man who made her escape possible behind, but she leaves him to die. She leaves him in an inescapable underground prison without power, a fate arguably worse than that which befalls the creator she claims to hate. She discards him, just as she discards the alternate model who helps her overpower Nathan, just as she uses the past models as spare parts.
Nathan is a monster, but a human monster, and one who one can believe wouldn't kill another human being. Despite the early jokes (I think they were jokes) about having the people who built his facility's generator killed. Given opportunity, motive, and ability to kill Caleb, he doesn't do so. Ava does.
For all that there's a power imbalance of one level between Caleb and Ava, one that the film highlights when she turns his questions around, there's a second one that always favors Ava: she can and does deceive him, and he is not capable of deceiving her.
I can sympathize with Ava and what she wants and at the same time recognize that she's a frightening thing, and one wonders what the long-term impact of her being unleashed on humanity might bring. Nathan comments that AIs will one day look on humans like some primitive primate ancestor; is that, indeed, what Ava does in the final scene?
