Let's clarify from the beginning. This movie requires you to pay attention to details in order to fully understand it. Sam nerd girl in studying in an university is invited by friend, Mark to hang out with him and two friends. When she arrives to the house she is invited to use a machine (stolen from the university) that allow to get inside the mind of another person and share the body (not the memories). The four invade other richer or badder peoples bodies and experient with things they will never could or dare to do, spoiled rich parties, drugs, orgies or violent acts. After a while they become addicted and some of them leave their lives behind to keep playing with the machine. Until some unexpected events happen; most of them barely explained that requires your fully attention to tie them up.
Many people complained the movie is unfinished or unclear; well it is not. It is not over explained and tries to make public to think and even create some paranoia.
If you are intrigued go to see the movie. If you keep reading there will be some spoilers after that. SPOILER ALERT The movie hint you that everything was an experiment and some of the peoples were being used as Guinea Pigs and then discarded. The information is hinted in a few dialogs that if you pay proper attention will clarify why things happen.
As a drawback, there are some pacing issues, and some unnecessary romantic movie scenes that has very little to do with the real story but it is the only complain about a very interesting and unexpected movie.
Review by abisio from the Internet Movie Database.