Good Thriller, Great Character Drama

Rating: 8/10 (22 December 2018)

Bottom Line: This is not a fast-paced action horror, but a methodical and deliberate character drama that is worth the watch if you are willing to follow the process of a character working through her internal conflict.
Although this is definitely a horror/thriller, I think some of the negative reviewers were expecting an action horror/thriller. That's not this movie. We don't get the backstory about the "monsters" because the movie isn't about them.
The theme of the movie is introduced in one of the very first scenes: this movie is about people's ability/inability to connect with one another. Every single character represents some aspect of that theme, some degree of connection. John Malkovich represents the self-centered a-holes who don't even want to connect with other people. On the other end are the ones who seek out connection with others even when their efforts are rebuffed. But they aren't cookie cutter characters either. The conflict created by the "monsters" forces all the characters to examine themselves and decide what kind of people they are.
The central focus is ultimately Sandra Bullock's character (Mallory) struggling with figuring out where she fits on that spectrum. The true conflict of the movie is Mallory's internal conflict. And without spoiling anything, the ending does give you an answer to that conflict.
Sure there are some unrealistic things in this movie. I don't understand why people would expect it to be any more realistic than, say, Jack Ryan, which is laughably unrealistic (but which I still enjoyed). But the actors were all pretty solid (even John Malkovich whose "acting" is usually abominable), lighting and direction were very good especially for this genre, and there were definitely some tense moments, even when I knew what was going to happen.
The real star, though, was the little girl. My goodness her ability to convey complex emotions just through facial expressions was absolutely incredible!