The Experiment. Definitely doesn't get the credit it deserves. While its extremely fast paced (even though some say its slow - which is not true), It has an interesting and intriguing storyline with great actors and some twists which, all in all, made me confused, excited, worried and even gave me an intense hatred for some of the characters. Whoever you are, I think you'll enjoy the film all in all. Try not to compare it to what most say it's a remake of - it's its own film and should be acclaimed for its self, without comparison to other versions. Fast paced and constant tension building throughout, which is just what I love in a movie. While it is not hugely thriller-like, or physiologically stimulating as may be expected, it is a great movie, especially for younger viewers (15+ as stated). Some explicit, adult natured themes should be expected, so kids should stay well away from this movie, however the worst stuff is fee and far between, so can be avoided - although you'll be missing some of the best parts of the movie.
Don't listen to those who say its awful - it's a great film, and don't knock it because of others opinions. Make your own judgement.