As other reviewers have indicated this is quite a confusing film. I went into it with the main twist spoiled, so I can see how it would frustrate the average viewer, making them feel betrayed by the first third of the film. But if you can look past that, it's actually not hard to appreciate the uniqueness of the overall premise and the bold attempt by young director.
One of the most unfortunate things about the execution of this film is that the flaws are as deep as the strength of the premise. That is to say, in the hands of a more seasoned and careful writer/director and a more balanced cast, the premise could have been made into an epic drama. Sadly there isn't enough foreshadowing of the twist (pay close attention to Tim's first conversation with the social worker), the script has some glaring weaknesses, the climax is thoroughly incomprehensible... et cetera.
Some viewers will have no qualms with the confusing nature of the film. It may possibly appeal to fans of David Lynch and similarish weirdo-directors. Certainly worth the time of someone who enjoys film for film, and psychological thrillers. Don't expect a masterpiece, but give it a chance.