This is a well written, well researched book. I was found the factual background to the story was what made the book fascinating (as someone else said it wasn't important). It is gruesome, but drug cartel life is gruesome. Because of this I'm not sure if it is suitable for young teenagers; they might see the excitement and danger of the lifestyle, and ignore the fact that they all end up in jail or dead at a very young age.
As a person who follows Mexican news and politics, it is the best book I've read in a long time.