Ok, don't read this book if you are looking for a real thriller, with unexpected twists and shock killer endings etc. As many people have already pointed out, the killer is pretty obvious almost from the second you meet them.
However, it is still a good book and I enjoyed reading it. I thought most of the characters were interesting, particularly the daughter Megan. She is a very realistic character, I don't know how old the author is but she obviously remembers being a teenager. Her relationship with her mother is well portrayed, very complex and real.
The story revolves around the murder of Diana, an abortion doctor, the investigation that follows, and the impact on the family left behind. The author gradually reveals some of Diana's past, which is interesting, including the death of her son, Megan's younger brother. There are few tense moments, but I was never bored either.
Basically, read this book if you are looking for an enjoyable fun (not funny) read that is easy to get through. Don't buy if you want to be challenged! Although there are some interesting angles around the abortion issue, the novel is mostly pretty straightforward.