I won't share my high concept reaction because it is a spoiler. See it unspoiled if you can. On the other hand, if you want to be spoiled or you've already seen it, Wil Wheaton's review says everything I'd want to say, and better.
Any number of times during the movie, I found myself thinking: "This is just what my Chill game is like on its best days." (No ego here, nope, not at all, move along.) Regular people in unimaginable circumstances, trying to deal and being heroic along the way. I have one player for whom Hud's remarks in the subway tunnel are perfectly in character. Some of their decisions are ill considered - even stupid - but they're plausible, and that's what makes the movie for me.
I also kept wondering if they were going to bring out a video game. I think it would make an amazing videogame.
I will be taking the pacing and sensibility of this movie into my game.
Go see it. Seriously. It's that good.