The novel, by Julia Leigh [1], is also wonderful. Recommended for fans of minimalist authors such as J. M. Coetzee, Philip Roth and Cormac McCarthy.
I thought the film captured the tone of the book extremely well, perhaps more than any adaptation I've seen. I loved the fact that the film explains very little (and neither does the novel), just lets the story tell itself through images and sound. Both are underappreciated gems.