Like Never Let Me Go (though I’ve only seen the movie), this is emotionally devastating, made even more so by Klara’s equanimity. Unlike replicants from Blade Runner or the boy from Spielberg/Kubrick’s A.I., Klara is quite content being a robot. But what a human robot she is! She is the only character in the book who expresses any sort of religious feeling---the only one who experiences a kind of enchanted world where the iron cage of modernity does not exist, where the Sun is an object of primitive worship. Ishiguro slyly plays along with Klara’s magical thinking in the scene where the Sun “heals” Josie.
What is really terrifying here, like in Never Let Me Go, is the setting being in the near future, where the new technology that broaches human nature (cloning in NLMG, artificial intelligence here) is not yet taken for granted. There are true believers (Capaldi), but the drama of the yet-to-be-converted (Chrissie), their struggle against the broach, and their acceptance of it in desperation (in both books, the despair of mortality), is terrifying exactly because it traces how we might accept similar broaches. It is a kind of horror where, in making small concessions here and there, we find ourselves in inhuman situations that we might never have accepted if the transition happened all at once.