I absolutely loved this film. It's a slow burn and more of a psychological character study. If that's not your jam, then this film likely isn't for you.
I found it incredibly tense, largely because of Phil (Benedict Cumberbatch). His presence is menacing and the lengths to which he will bully and torment his favorite targets is unclear. When he feels threatened by his brother's new wife and her son, he steps up his torment. He is especially keen on proving that Rose isn't good enough and zeroing in on her weaknesses, like tormenting her with a song she can't quite master. His performative masculinity is all about tearing others down to appear strong and hide what he finds shameful about himself. He is almost personally insulted and angered by anything remotely feminine.
The actors all give excellent performances and New Zealand is a fantastic stand in for Montana. (I've seen some reviews critical that it wasn't filmed on location... Um, ok. As if Hollywood never pretends, say, Vancouver is LA, Seattle, New York, and the Battlestar Galactica. Might as well be critical that they used New Zealand instead of Middle Earth.) The movie lingers on panoramic shots of sweeping hills and grassland. It highlights the isolation of the characters, despite being surrounded by ranch hands, household staff, and terrifying family.