"Is surviving living?"
That's the question It Comes at Night answers.
As for the film itself, the forty people around me hated it. "Awful." "Can we get our money back?" "That was terrible." A cascade of negativity as we shuffled toward the exit.
As for me, I loved it. Tremendous tension, foreboding, anxiety and ambiguity, as there often is with great horror.
My only knock is duration. Clocking in at 91 minutes, it's something best watched at home. By the time you settle in and come to terms, the end credits are up.
Presto-blammo-finis.