I read this during a pretty dark time in my life recently, so perhaps that's why this book seemed to strike a particular chord with me. It's easy to sink into the pain another character is feeling when you're going through something yourself. Granted my experience was very different (death of a grandparent), but somehow this all came together to form a book that I really enjoyed. 
 I think that part of what made this stand out so much was that none of the characters were really all that likeable. All of them had gigantic flaws, especially our main character of Libby. When you consider that she's lost everyone in her life via a tragic set of murders (mother and two sisters dead, brother in jail for the deaths, aunt is alienated by Libby's new angry personality), it makes sense that Libby is the way she is. It's kind of a character for those of us who see these murder survivors on television and get amazed that they're not more jaded and bitter than they appear. 
 The interesting thing about this book is that although it is a mystery, it's more of a technical aspect than anything else. It seems to sit in the background as a plot device to move along the more important aspect: Libby finally confronting the demons of her past and finding it in her to actually connect with the people around her rather than just tolerate them. See, Libby is a character that has essentially given up on life even if she doesn't realize it. Even though her actions are initially funded by financial issues, you can see where she's eventually somewhat doing this for herself and her brother over time. 
 It's probably not a book that everyone will like, but it's one that has made me eager to finally start in on all of those other Flynn books that I've been meaning to read for the past few years.