I love movies that make me want to go back and immediately re-watch them, to see exactly what so-and-so said when, and figure out, did they really structure this movie as intricately and well as it seems? Which, the makers of this one did. After marveling at and admiring (or hating, your choice... I marvelled and admired) the late-story plot developments, unexpected questions resulted which I wanted to find good answers to. Questions mostly about Goodman's character... particularly what was he thinking at points x and y and z? What specifically was going on with him throughout... and even before the story we saw started?
This was a hard movie to afterwards convince other people to see, because to tell them much about what they're in for, ...well, you can't really, without spoiling it for them.
I'd seen Room around that time, too. Both are great, but this slightly kindred girl-in-a-very-tough-spot film is so much more enjoyable.
Btw, in the bluray special features there's a quick glimpse of a schematic of the bunker, with even the year noted for when Goodman's character made each addition to it. This was helpful in my minor obsession to figure out his history as specifically as I could.
But don't let all this post-viewing puzzling out of story details put you off it, you can enjoy it greatly without all the revisiting of it that I did.
But I do love a smart movie that engages and also challenges me.