I owe my good night's sleep, my husband's, and most importantly, my twins, sleep to this book (as well as the original and Babywise if I'm being honest). Following the principles mentioned in those three books helped me get my twins sleeping at least 11 hours through the night before they were 3 months old.
That being said, I, having read the original, came prepared so I was just looking for information about getting both of my twins to sleep at the same time amd through the night. I do think that this book is missing a lot of information compared to the first one, but I did want it to be precise, as I can't say I liked how long and redundant the first one was, but I think it was taken a little too far.
Especially with the different techniques and what works for which age. Also, this book doesn't give you much info about what happens after your kids get past a certain age (3 I think?), you still need to manage your kids' sleep after that, you know.
So yeah, it's good, but just don't depend solely on it.