At first the premise of a book following two characters through 20 years by showing the same day every year sounded interesting. After reading a few years I found that I was more interested in what was happening "off-screen" than what the author was describing. I wanted to read about painful breakups and career successes, not have them alluded to months after they've happened.
The first half of this book dragging and I really couldn't get into it. After about the mid-way point I started to enjoy reading Emma's sections and wanted to skip Dexter's. Throughout the book it is difficult to understand why Emma continues being Dexter's friend. He clearly looks down on her and does not value their friendship as much as she does. Sure, he slowly realizes how important she is, but by that point any sane woman would have washed her hands of him.