While the man-eating fungus-body-snatcher-plague is by no means original, the serious portrayal of a zombie apocalypse in The Girl with All the Gifts is one of the best. It's hard to believe they managed to do all they did on screen with such little budget (less than $5 million). The derelict natural-takeover landscapes are stunning and the fungal evolution is otherworldly and interesting. There's some extremely tense moments in this film and it achieves horror without reliance on jump scares or gratuitous gore.
All that being said, the film's finale is poorly executed. Did the soldiers just decide to abandon all reason for the sake of wrapping up the plot? The teacher just accepts the near total genocide of the human race after a few tears?
In the end, the Girl may be somewhat human, but she is absent of any humanity... And in this case, quite "literally worse than Hitler."