Cummins has written a riveting, well-researched story about the experience of Mexican migrants from their pov. It is a good story and well told. The characters have a level of complexity that avoid simple stereotypes.
That being said, there are some annoying stylistic issues, including head-hopping that becomes distracting. Nevertheless, Cummins's storytelling is solid and the subject matter--how easily life can collapse in a lawless society where narco traffickers command such authority, where there is so much corruption and even casual conversations with the wrong people, do leave you vulnerable--is timely and vital. I enjoyed the story more than the execution.