Guide to Healthy Pregnancy from the stables of Mayo Clinic is an easy-to-read and a straightforward book. It performs the role of a reference book for practically any problem that you might encounter during pregnancy. However, I felt the part which talks about pregnancy was informative but too dry. By dry, I mean there is not much detailed info in each section. That said, the book does not waste space on unnecessary things either.
My only issue with this book is that in the present day and age and with technological advancements at least in the field of obstetrics, this book is not worth spending your money on. You can get much better information on babycenter.com.
All in all, a book that I would not spend my time and money on.