I read this book last night (it's very brief, I read it in a couple of hours) and am seriously thinking of reading it again today. I can't stop thinking about it. The way the story is told, the characters, the way it kind of made the hairs on my arms stand up. It felt like an experience more than just reading. When I finished, I felt a bit like I did after reading Requiem for a Dream (ie, put through a wringer of self-destruction, despair, and violence that begets more violence). Still, it is a story perfectly told and perfectly concluded.
My only criticism is that the writing is awkward at times. There were a lot of missing pronouns and sometimes the pronouns were wrong (for example, the character Luna was mostly referred to as "he/him" but in a few places referred to as "her"). I'm guessing that the translation from Spanish to English just wasn't great. If only I was fluent in Spanish so I could read the original text!