This should really be a 3.5 (and not a 3) star rating. I liked this book much better than Gone Girl and I gave that a 3 star rating. It was compelling and entertaining and had enough potential bad guys that it kept me guessing for a while on the who-done-it front.
There were quite a few annoying bits that kept it from being a 4 star. First, I thought Libby was just trying too hard as a narrator; she is hyper self-aware (about her anger, her misanthropic tendencies, her kleptomania, her depression) but she also wants to be good and wants to be liked and underneath it all sort of sounds like a psychoanalyst who can see through her own games. It just didn't feel real. It would have almost been better if the chapters were written in 3rd person (as the Patty and Ben flashbacks were written) and Flynn could have made the commentary.
Similarly, I didn't think all the parallels between Krissi Cates and Libby ("They were trying to make you comfortable, they thought the harder they believed in you, the easier it'd be for you,") as little girls being manipulated by the adults to incriminate Ben were so necessary. It felt way too overt, like Flynn wanted me to think "Wow, she is being so insightful here" and instead, I just rolled my eyes. The same thing happened with Lyle confessed to accidentally starting the forest fires in CA in 1999; this was a completely unnecessary scene for them to bond over "that feeling of something getting completely beyond your control."
Second, during the first encounter with Len the Lender (besides the alliteration being annoying), Patty says her maiden name was Krause (this is also confirmed later when Diane introduces herself to the cop as Diane Krause), but when she talks about her parents she calls them Ed and Ann Day and she talks about the Day characteristics and the Day farm. The kids are Days and Patty is now a Day because Runner is a Day....the farm was the Krause farm. Not a big deal, but one of those things that nags at the back of my head as I read.
Third, I wasn't sure that all of this needed to happen on the same day. I get that Patty's impending foreclosure is how she meets the Angel of Debt which actually causes the murders, but the added drama of Ben as a child molester seemed unnecessary (Diondra would have wanted to leave anyway just because she was pregnant and she could have just bullied him into it). The build-up between Ben and Diondra could have happened earlier in the week and his departure could have even been more planned and then just coincided with the Angel of Debt's visit. It just felt like too many red herrings...Flynn was trying to throw so much at the reader so that she could keep a lot of potential murderers floating and it was just too unbelievable and coincidental that it would all happen on the same day.
Finally, I was not sure that I ever understood Diondra's motivation. She is sort of painted as a spoiled rich girl with neglectful parents but then she turns really mean quite quickly. She is so worried that her dad is going to kill her (really? he will actually murder her for being pregnant?), but she doesn't think it will bother him that she runs away? He won't try to find her? At one point Flynn says that Diondra never phoned Ben and he wasn't allowed to call her so she had to go to a payphone at the mall to talk to him. Really? Her parents are gone most of the time? And ultimately Libby finds Diondra with Crystal in some random farmhouse...where did they get the money to live for those 25 years? Why is Diondra so attached to this daughter (I kind of figured her for giving the baby up for adoption once she was on her own)? Why isn't Crystal brain damaged from all the junk Diondra put into her body while she was pregnant? The whole Diondra piece was a tool to explain Ben's willingness to take the rap, but her character was too weak and unexplained to support the details.
Overall, a good read. Entertaining and compelling, but not really insightful or philosophical.