Personally, I think there is no better reference for a woman who is pregnant. Granted, they are a little paranoid about some things (such as taking medications and what you eat, etc.) but overall the information is very helpful, particularly with its question & answer format. I highly recommend this book.
Most women consider this the pregnancy Bible. :] I have read it with each of my pregnancies and while I don't agree with a lot of the "do what the doctor says every time" mentality, it does have some great info about each stage of pregnancy and what the baby is doing, etc. I enjoyed it for that part.
As a natural childbirth educator in training and a normal birth advocate, I cannot endorse this book. While there is some very good information, there is a definite bent toward extremely "medical" childbirth.
I hated this book. I tell everyone I know who's pregnant never to read it. It focuses so much on every little thing being a sign of disaster, almost all of which are the mother's fault for not eating the right thing/sleeping the right way/whatever. There is no joy in this book, only gloom. Try the Sears & Sears Baby Book instead!
I think that this book is one of the worst pregnancy books that I have ever read! Every chapter is full of what can go wrong with your baby, the pregnancy and birth. Yes it does have lots of pregnancy info. But it represented so negatively, and doesn't even come close to representing the wonder, joy, beauty, and anticipation that should be felt by expectant moms.
My favorite pregnancy book is the Mayo Clinic Guide to Pregnancy. I read this book during my first pregnancy, and I though it was great, answering all my questions, but it also made me depressed and scared. It wasn't until my next child that I got other books to compare to it. There are many other books that are far, far better than this one.