I was actually surprised after watching this movie, having firstly noticed the given low ratings.
Starting with the characters, the difference in the way each one of them feels about the environmental problems is clear and straightforward. While Harmon, being an ex-con, performs his role in a more detached way, Dena, and mainly Josh, possess deep feelings about them. Dena learnt about them and made up her mind supported in what she claims to be scientific facts. Josh appears to have a more romantic and purist approach, despite his paranoid outbreaks and trust problems. This actually helps the viewer to start building an idea about how each one of these characters will react to the approaching outcome.
OK, it is a slow paced movie, which I don't see as something necessarily bad. Actually, I think it contrasts beautifully with the sentiment of urgency that the problem demands and which they want people to acknowledge. Also, about the kind of numbness in Josh expressions during almost all the scenes, I simply cannot see them as emotionless or empty. I rather think (and felt) that he was the most engagingly involved and disturbed about environmental unbalances, almost in a traumatized way, which I think is reinforced by some plan shots, silent and numbing, taking a few more seconds than we are used to.
Ultimately, it is a movie about the human condition, about good people, with good reasons, doing wrong things.
