I read this book thinking it would be nice to get my infant on a schedule from the beginning since I also have an 18-month old, but, the scheduling they suggest is completely unrealistic for young babies and it was much more frustrating to try to do everything "by the book" than it was to just go with my natural instincts (and incorporating information from other books.) My 2nd baby turned out to be a pretty high-needs child (completely different from my 1st which shows why this parenting technique simply won't work for all kids) and we all did a lot better after I decided just to "wear" her in the Bjorn most of the time. When she got older (around 9 weeks) she naturally outgrew her need to be held constantly and turned into an incredibly happy baby who now cries only when she's tired or hungry. From the beginning she was a great sleeper and now at 12 weeks, she takes regular long naps (two 1-hr naps and 1 2-1/2 hr nap) and sleeps regularly from 9p-7a, waking up either 0 or 1 time for a feeding (this is with no crying and on-demand breastfeeding.) I consider myself a moderate person, I'm certainly not dedicated to attachment parenting and I'm actually a big fan of scheduling kids b/c they really do seem to prefer having a set routine, but, I think it should be done on an age-appropriate basis (starting around 3-4 months at the earliest), taking the individual needs of the baby into consideration. I also cannot imagine going a lifetime without experiencing the pure joy of rocking your child to sleep and holding a helpless tiny life in your arms while they slumber away. If you follow this book to the letter, it seems to me a lot of the joy of parenting an infant would be taken away -- it's such a short period of time, it's a shame to waste it.
With that said, you're obviously looking at reviews of this book because you need information on your child, so, I have some other recommendations.
For sleep information, I highly recommend Healthy Sleep Habits, Happy Child, by Dr. Marc Weissbluth, a pediatrician. The Ferber book (also written by a Dr. who is a pediatric sleep specialist), Solving Your Child's Sleep Problems, is also very good. They are both cry it out books, but, with much more age-appropriate and scientifically based recommendations. (For example, a baby simply isn't developmentally capable of learning to self-soothe to sleep until they're at least 12-14 weeks old, so, it's pretty nonsensical to let a child younger than that cry themselves to sleep because you won't see any reduction in crying until they can learn to self-soothe. If you do controlled crying at an age-appropriate time, they may cry a little, but, the crying will get less and less very quickly because they can learn to soothe themselves to sleep.)
If scheduling your newborn is your main interest, I think the Baby Whisperer book is much more realistic because it is much more flexible and teaches parents how to watch for cues their baby is sending, though, I think even that book is best suited for slightly older babies (2-3mo+), even though the author thinks you should start her routine from birth.
If this book is appealing to you because you have a fussy baby and are at your wits end, check out The Happiest Baby on the Block by Dr. Harvey Karp or The Fussy Baby Book: Parenting Your High-Need Child From Birth to Age Five by Dr. Sears. I don't agree with everything Dr. Sears says, especially his pro-co-sleeping stand, but, I do think he's right on point about meeting the needs of young infants (under 3-4 months old) who are fussier than average.
There is some good information in this book and I'm sure it's helped a lot of parents, especially new parents who haven't been around infants very much, but, it also has some really really bad advice. (I agree with the reviewer who said you should try to go 4 hours without so much as a drink of water and see how happy you feel.) The other thing that makes me crazy about this book is that it is completely ridiculous to think that you know more than your baby does about when he needs to eat. Believe me, from day 1, your baby is fully equipped to tell you when he needs to eat. Please don't let this book convince you otherwise. (Now, sleeping, that's another subject and I highly recommend reading Weissbluth's book about sleep.)
If you do end up buying this book, PLEASE PLEASE PLEASE, inject your own common sense into this approach because I could really see how following it precisily could lead to disastrous consequences (especially during hot summer months). And most importantly, try to ENJOY and LOVE your children and don't think of raising kids as a war between you and them. What they need most of all is your love and the confidence that you will meet their basic needs. The first few months are all about developing confidence and trust and making them feel secure in this world that's so scary to them compared to the in-utero environment they'd been living in for 9 months. I don't think this book helps parents accomplish that in the least. Trust yourself, love your kids, read a good sleep book written by a doctor, and you'll be a wonderful parent!