Among Friends has some great things going for it. The story is interesting, the actors (for the most part) do a great job, and some of the directorial decisions make this a fun ride. The movie does borrow from a handful of other movies. Saw, Would you Rather, and Deranged being among them. But the movie distinguishes itself and is better than some of the movies it shares similarities with.
However, as much fun as I had with Among Friends and as invested as I was with the characters and their situation, the ending kills this movie. Simply because there is no conclusion. The movie just ends. There's no reason for a film maker to not create an ending for their movie. As the viewers we've invested the time into getting to know the characters and anticipate how the story unfolds. It's the writer and director's job to make sure that the story has a satisfactory conclusion. Not always happy, not always straightforward, but an ending that makes me glad I invested the time into watching the movie. Among friends doesn't have this. I just felt frustrated, cheated, and completely unsatisfied.
In conclusion, I can't recommend this movie. It's frustrating how much potential was displayed and then squandered.