I'm normally not attracted to SHTF (Shit Hit the Fan) films. Especially big ones because the endings are so inconclusive. This one was scary because that 2hr movie length too. I mean, be honest, nobody wants to spend 2hrs watching something and come away without a conclusion. Good, bad, meh, whatever but end the damn thing. i got over that reading comments, reviews and hearing my favorite couple hype it for weeks.
I DO enjoy the messages of SHTF movies. Discussions of what people should do, will do, won't do are wildly entertaining. Leave the World Behind dug in with this concept. On the surface, you're caught up in the audacity of characters. Then, the storyline develops certain people and you're picking sides, choosing friends. Somehow, it slides the family relationships into the conversation, husband-wife, father-daughter, sister-brother, they all make caneos. The film challenges your ethics, questions your fears. It was quite impressive.