Right out of the gate I had trouble believing a 32 year vet of border patrol couldn't speak conversational Spanish, never mind understand basic Spanish words aside from curses, but after a few episodes I got into it.
Very well acted, and the portrayal of the cartel feels authentic. I'm looking forward to next season.
Edit: it has a "Breaking Bad" feel: a guy who starts out doing something wrong but for a noble reason to find himself on the moral slippery slope...