The idea of this book is pretty sweet: Christine wakes up each morning with total amnesia, and the only thing she has to hold her life together is a journal she has been keeping which contains everything she has learned about herself. So she has this fascinating memory problem, which means she is completely defined by the book that she is writing. Sounds great!
Unfortunately, the execution was so bad. Not only was the writing terrible, but I could not at any point agree that Christine writes her journal in amateur-novel style. NOBODY would do that. Obviously, she would write it in point form (remembering that she has to read the whole thing every morning), but I was willing to suspend my disbelief and just go with a journal that has lengthy descriptions and even dialogue in it. But I still kept getting angry at Christine for wasting her time on so many words. She is constantly writing things like, "I heard his key in the lock, the door pushed open, feet being wiped on the mat. A whistle? Or was that the sound of my breathing, hard and heavy?" Over and over I kept thinking that this can't possibly be a journal. Nobody wonders after the fact whether that noise she heard was a whistle or her own breath! You just write down what it was, and move on. Better: if you are both a) rushing to write everything down before your husband gets home, and b) aware that you have to read the whole thing tomorrow morning and every morning after that, you skip that crap and GET TO THE POINT.
Finally, the ending. It's common for film directors to take a clever premise, explore it thoroughly, and then resolve the problems posed with straight-up violence. You know what, though: that's really boring, and also it's what your audience thinks is probably coming, so don't do it. I skimmed. Part III of the book could use a complete rewrite.
Despite how disappointing this book was, I kind of enjoyed reading it. There was genuine tension in the plot, and the author did a good job making sure I didn't know whether to trust the main character's story (she is told she has a history of paranoia) or her husband's (her journal says "DON'T TRUST BEN" on the front page). It was an unsatisfactory novel, but a satisfying airport read. So, I would recommend it maybe if you need something to pass the time in an environment where it's hard to focus, but definitely not if you have something good waiting on your bookshelf.