From the other comments, it's clear people are quickly turning into a hungry media consuming, "ENTERTAIN ME NOW", Wall-E era people. If it doesn't have flashing lights and a quick pace, it's deemed "boring" and a waste of space.
Here's a real review - first off, the score is phenomenal. Huge throw back to a bygone age when music was a part of the story, and not just a signal of scene changes. Its forboding tone sets the stage perfectly.
It's a small cast, but an excellent one. To address the comment that Segel doesn't play a convincing bad guy - that reviewer embarassingly missed the point that Segel ISNT a bad guy. Plemmons is a character actor, and fills out this role well, while Collins does a great job pulling you in to how she changes emotionally throughout the film.
It's true this would make a great play, but I'm not sure why that counts against it as a film? Seriously, people's reasoning for why they rate it so low is mindboggling.
In a nutshell, this is a great story about how 3 very different people would react when put into a stressful situation. It's a story that reveals the true colours of each character, and brilliantly leaves you guessing until the very end.
It's well worth the watch - just don't expect explosions or super powers.