Although there are moments of extremely dark comedy early on, after a certain point, the humor stops and with it any form of release from the almost unbearable tension of the film's third act. (film.avclub.com)
Smarter than hell about its sources, it employs all of them to a full seventy minutes of unbearable tension capped by twenty minutes of payoff. (filmfreakcentral.net)
With very little action, this film builds almost unbearable tension by carefully examining some moral questions in a precarious situation that's based on true events. (contactmusic.net)