Although the story was incredibly interesting, I had trouble relating to much to the characters. They all seemed to be driven by only one personality trait, which got quite old. People have more depth than that generally. Matt and El Patron were both driven almost entirely by the desire to preserve their lives, although El Patron includes with his life his hoard. Maria wants to save all creatures who cannot save themselves. Tom only cares about screwing with people. None of the characters were particularly likable, even Maria, who could be too trusting of people despite the evidence to the contrary.
Recommended for fans of dystopia and alternative futures. Especially recommended if you liked Neal Shusterman's Unwind.