I saw this at an Italian film festival past week...surprisingly great. 100% diolague driven but the acting was superb and even in subtitles I wasn't taken out of it. Great plot and twists and for a film that takes place in a single room that's tough to pull off.
Non spoiler plot: a group of friends are having a dinner party and they discuss how well they know eachother... so well, that they should (as a game) put their phones in the middle of the table and read any text, speaker any call, etc that they get... shyt gets hairy. Hillarious at times too.
This movie was great; really, really well acted. A solid A- at worst.