I would actually give this a 2½/5, but rounding it down to a 2/5 because I get more out of a 3 star movie. A huge chunk of what makes this movie great is missing.
I'll just say that what this movie does, it does decently. The shots are beautiful, scenes flow together nicely. This movie aims to build up tension, and it does just that. The problem is that's pretty much all it does with little pay off.
There's not much explanation for anything happening, although it's clearly intentional that we are meant to discover the answer for ourselves as we go along; there are almost no moments of complete discovery or even partial discoveries until the very end of the film (and even then, you're still left a little puzzled). It's a constant theme of speculating what's happening to the point where you start wondering if things even happen for a legitimate reason. Everyone has their own speculations but nobody knows what they're talking about. Power plants, right?
Way too many times, George, the only person who seemingly knows something, would attempt to hint at what he thinks is going on, but constantly stops short in an annoying fashion, almost like those ads where the dating coaches promise to tell you "the ONE thing to do to win the girl by the end of this skippable ad" only to not tell you it, then you feel like you've been conned into giving them watchtime.
While I did say the movie did things well, it still did things poorly. The teenage boy randomly hints about a creep watching Rosie from the shed... felt like the movie didn't know what it wanted at that point. When his teeth fell off, he was way too relaxed about it; "I'm not sick, my teeth are just falling off". The conversation between the girl and husband wasn't needed. The idea that everyone seemed untrustworthy was interesting at first then kinda just fell flat, then was unnecessarily brought back by the teenage girl's expositional dialogue.