Jesse Snoddon’s review published on Letterboxd:
A thematically layered look at the lengths people will go to in the pursuit of happiness, Lamb is more of a cerebral and philosophical slow burn than a high stakes horror. This isn't to say the film doesn't have a consistently tense undercurrent. It's clear that both foster parents are actively ignoring the warning signs around them about their unorthodox daughter, and the more they treat their situation as completely normal, the more intense the foreboding sense that something dark is approaching becomes.
Surreal and contemplative, Lamb works as an effective commentary about the dangers and potentially disastrous consequences of man's transgressions against nature. I'm not completely sold on this one, as it has some drag to it and the central premise feels a bit gimmicky at points. It feels a little cold and difficult to engage with on a human level as well. The scenery looks beautiful though and the payoff to the film was crazy enough to make the ride worth it for me. I can see liking this more or liking it less with a rewatch and some thought. It could go either way.