This is one of those movies that you watch and slowly "connect" to its reality. Many people disliked that. It was either to slow compared to most of the movies today or too intense an experience to people that don't like the feeling of immersion into something else. However, from what I am sitting, it was a great movie.
First of all, one must take a step back from the usual reviewer practice and take into account that all the actors in the movie are Mexican and so is the writer/director. I don't know what budget the movie had, but it was well done in acting, atmosphere, plot, details and special effects. Winning the Sundance festival (and not being about crazy people) should also count in its favor.
Second of all, I really enjoyed the movie. It has the feel of films like Blade Runner, only it hits really closer to home. Luis Fernando Peña was a real good choice for the main role, even if it wasn't a very challenging one. As in many good movies, the main character was the idea, the plot, and the actors were just slipping into their niche.
Bottom line: this is a sci-fi movie that needs to be seen. Whatever faults it has, they are far surpassed by its qualities. The social message is just as important as the vision of a future where we can have whatever we wish for, only that we wished wrong. See it. It is worth it.