I saw the awful reviews but decided to try the movie anyway, because it sounded different from the typical gore horror or psych terror or techno thriller. I'm glad that I did. It is in fact none of those things, although it ends up listed in those categories. I think that may be a reason for the bad reviews. If you're expecting gore, jump scares, psychological terror, or action adventure, you'll be disappointed.
What it is, and does a good job of being, is a slice-of-life picture of three people stuck together in an unexpected situation, how they interact, and how it changes their lives. The actors do a great job of portraying the characters and how they react to each other and their circumstances. There's a tension between the 3-way simultaneous conflicts and attractions. There's also a nice little twist revealed at the end, and the closing kind of completes a circle back to the beginning, which is a nice touch. Overall, it was a good experience.
I would've liked a little more background on the characters. While they are solidly-played, you get a few interesting hints to their backgrounds that are never really explored. But the movie is already a bit slow compared to typical action-oriented movies; more exposition could've lengthened it perhaps too much. So while I'd've liked to see more of that, maybe they did the right thing by cutting or not adding it.