One hell of a first novel. Santuario is a story about cultural distance, corruption, and desperation; there's also a developing gay relationship between the leads. That order, I think, is the most satisfying way to approach the novel: it's about the problems the island of Santuario faces and the ways that the main characters deal with them first and foremost. Readers who want a romance first with the murder plot as a side dish might be frustrated; I, on the other hand, really like a story where the romance doesn't overwhelm the characters' other attachments and priorities, so the balance worked just right for me. 
 I really enjoyed the way the complexity of Santuario's situation was portrayed. It would be easy to make the familias 2-d evil, oppressing a virtuous populace, but Gordon complicates that assumption a number of times during the story; both main characters stumble on their own assumptions more than once and have to work around having their ideas challenged. 
 Comparatively, I found (view spoiler)[Alex's reactions to finding out Bengt was gay somewhat opaque; it took a while for me to have a clear sense of why he was so upset and how he could read it as a betrayal of trust. (hide spoiler)] But that may well be clearer for other readers who have better background in the cultures that Santuario-the-nation is based on, I'm not sure. 
 Overall I'm very glad that this story was marked as the first of a series, because I'd love to see what happens next -- both to the main characters and their world, which is in a really crucial point of transition as this story unfolds. Good luck writing Santuario #2, G.B.!