To be honest I'm not sure how to talk about this film without spoilers. Apparently it is based off an ancient Greek story, but the most obvious point of comparison would be Sophie's Choice, if only because he's asked to chose among loved ones. Of course, I never found Sophie's Choice, or this choice, that hard because obviously you let the boy die because ugh, boys. As a rational calculation, arguably you choose the youngest because less has been invested at that point.
In typical Lanthimos style, there is an uncanny nature to the setting. The delivery is abnormal, the dialogue is frank and emotionless for large portions at the start, making you throw out your expectations of how this world works. Certainly at the start the impression is that Steven (Colin Farrell) might have a creepy thing going on with Martin (Barry Keoghan). But then as you see these weird interactions persist in many situations, that sexual implication fades and we find out the real context and the tension builds. I could easily see this taking a turn like The Mist...posing a stern ethical question and having a reveal that makes it moot and pointless, but I guess here they stick to the supernatural angle.
I would say this struck me less both emotionally and intellectually than Dogtooth and The Lobster. It is a film of some interest but ultimately not a rousing success.