This isn't my favorite, by far, of Jodi's novels. However, I suffered severe postpartum depression, and the mother in this story experiences her own version of that illness. It is a pretty realistic portrayal of what PPD can do to a person and her marriage/life.
I experienced postpartum depression with my first child, so I can relate both to Heather - which gives me some insight into her life - and to the character Paige. This novel is more than just a PPD experience, though; it explores the parent-child relationship in many ways - and I think that's something to which we can all relate.