Joseph Gordon-Levitt is a phenomenal actor. One of my absolute favorites. His half of the film I love. His character is unique and twisted, but as a viewer you understand. You sympathize rather than judge. His relationship with Michelle Trachtenberg is compelling and her concern for him palpable. His half of the story I'm deeply invested in.
The other half - not so much. If you're unfamiliar with the story it's essentially about two boys who are sexually abused as children. This drives Joseph Gordon-Levitt's character to become a male prostitute, obsessed with older men. The other boy, played by Brady Corbett, doesn't remember exactly what happened. He comes to the conclusion, perhaps based more on denial than anything else, that he was abducted by aliens. The problem I have with his half of the story is that the audience knows from square one what really happened to him. We know he's just wasting time befriending a woman who believes she too was abducted. (Mary Lynn Rajskub) We know what he'll find out when he finally manages to speak with Joseph Gordon-Levitt. And his character isn't anything new. He's essentially asexual, afraid of physical intimacy. And the acting isn't all that great. So his half of the story labors on to the inevitable ending. The saving grace is when he befriends Eric, the boy left behind by Joseph Gordon-Levitt and Michelle Trachtenberg. Eric is a good character, if somewhat typical.
I recommend this film to people who aren't easily upset by such subject matter. There are some harsh scenes - nothing is shown but the voice over is fairly specific about what's going on. It's not pleasant. But if you enjoy Joseph Gordon-Levitt (and you should!) this remains one of his best performances.