I read this book when my oldest was an infant and I can tell you the book was great. The part I remember most was right in the beginning. Miss Manners divides parents in to two types. There are the type who beam when they see their children, love them to death, and think they are wonderful, then there are the type who consider their children difficult and a terrible inconvenience. The ones who think their kids are wonderful wind up with children who want to please their parents and become great people with far less difficulty.
For the record I have one in college and two are still teenagers. They are not particularly easy, in fact people gave me a very hard time when they were younger. Following the advice int his book worked and we developed a calm and happy household. My critics who followed various popular child rearing methods from experts now have difficult and rebellious teenagers and my kids are mostly easy excepting a few perfectly normal hormonal eruptions. I constantly get comments on my children's wonderful manners. My daughter who is exceptionally oppositional recently complained that she cannot have any fun rebelling because everything is her choice. I am not permissive, they do not choose consequences, but from a young age I have had total faith in their ability to figure things out from their own experience and ultimately make good choices as they get older.
Other books that helped me were James Dobson's "Dare to Discipline" and his book on oppositional children. People around me considered my kids very difficult from about birth to age 6-10 depending on the child, so I can assure you parents out there that these methods really do work and Miss Manners is not starting out with Perfect Children, she is teaching people how to develop them.