This has been the most helpful book I have read on the subject of child sleeping patterns and I wish I had read it before our baby was born, because as a previous reviewer has pointed out, there are issues with layout, repetition and consistency. One needs time to digest and understand the book and it can indeed be difficult to follow if one is already sleep deprived. For example, key recommendations highlighted in boxes on some pages, such as "Never wake a sleeping baby", are qualified in the body of the text (wake a sleeping baby if to let her sleep would interfere with that child's daily sleeping pattern): this can be initially confusing and we often had to read the same chapter a number of times in order to appreciate the subleties of the advice and the nuances for our own child. I didn't expect a "one size fits all" solution, however, so a certain complexity to the book seems understandable.
Such difficulties aside, we relied heavily on the book at months 3 to 4 and it helped us to understand the reasons for the changes to our baby's sleeping patterns and the importance of helping her learn to get to sleep by herself. From being woken every 2 hours throughout the night and our daughter being unable to nap for longer than 40 minute periods during the day (and consequently behaving as if she had attention deficit disorder and being generally a bit miserable when she was awake), we now at 8 months have (and have had since 4 months) a happy, relaxed baby who sleeps 11 or 12 hours at night and naps well and easily during the day: this has been literally life-changing and marriage saving.
I was very reassured by the extent of scientific research cited in the bibliography and my partner in particular was happier to accept advice from someone who could point to supporting research than from other parenting "experts/personalities" with books on the market. A friend lent us the No Cry Sleep Solutions book which I initially found helpful but which left me feeling intensely guilty if our daughter cried at all and led to my trying physically to soothe or feed the baby to sleep at increasingly more frequent times during the night until we were both exhausted and frantic. To understand that limited, controlled crying in certain circumstances can within a few days establish a child's independent ability to sleep - and the reasons why, stripped of judgment not based on research - was incredibly helpful to us. Our daughter has cried much less, both during the day and at night, since she learned to sleep by herself.
The book deals with sleep issues from birth to teenager and provides considerably more detail than any other book on the market which I could find. Its conclusions are consistent with those of a number of other authors: the difference with this book is that the reasons for the advice given are fully explained and the supporting research cited, so that one does not feel that one is experimenting with one's own child. This is particularly important in the highly emotive context of allowing one's child to cry in certain circumstances.
Despite the qualifications mentioned above, I have given this book 5 stars in this review because of the effect it has had on our life and on our daughter's happiness.