The story is wonderful, and the way it's presented is both unique and interesting. Ms. Delinsky has a writing style and a way of exploring contemporary women's issues that few other authors can match. If you haven't read this book, by all means do so. It will probably make you smile and definitely make you cry.
Having said that, I found Jack to be a much more sympathetic character than Rachel. Yes, he has flaws. And, yes, he carries much of the weight of responsibility for the loss of their marriage. Much...but not all.
I didn't feel that Rachel ever owned up to her own contribution to their divorce. After all, she walked out on Jack. Without explanation. She took his daughters and went someplace where she could be more creative. But never - not once - did she tell him why she was leaving or what he was doing wrong. She expected him to read her mind in several situations - to anticipate needs she never expressed - and when he couldn't, she punished him. Jack had to discover Rachel's feelings secondhand and I think that was an injustice.
That was the weakest link in this book. The relationships between Jack and his daughters and Jack and Rachel's friends are developed beautifully (and, incidentally, comprise much of the book). Likewise, Jack's path of discovery and growth is believable and heartwrenching.
Jack's character alone makes this book worth reading.