I had a problem: I was hired by a top ad agency to be their in-house A/V specialist, and while the job included things I'm good at like editing and videography, it also called for me to use a digital SLR and I never mastered the disposable point-n-shoot. I knew I could take pictures of landscapes, sunsets, and bowls of fruit because those things are patient and don't mind if you take hundreds of shots trying to get the exposure correct. I had an urgent need to learn how to fake a portrait and snap a fast candid shot, so I got this book. It is amazing! It's well written, covers everything from soup to nuts, and has some great real-world examples. It doesn't insult its readers by talking down to us, but it isn't full of jargon like most of my video manuals are.
I realize I'm probably the exception to the rule - I know how to use a digital SLR now and I do it professionally everyday, yet I still need a book like this to give me some pointers to improve my shots. I know that the primary audience for this book is the aspiring amateur, but I'm very pleased that it's written in a way that is approachable for photographers of all levels. I'm going to be keeping this book in my collection.
As an aside, soon after I bought this book I started dating a very nice woman who's father is a huge bird photography nut. This book gave me some great gift ideas for him! I tell you, this book is a gold mine!
Update:
Well, I married that girl, gave my now father-in-law this book and he loved it. He's expanded his repertoire to include local sports and has gotten his photographs into the local newspapers. I'm not crediting his successful career-after-retirement to this book, but I do think there's a correlation. For my own part, I can honestly say the techniques I've learned from reading Portrait and Candid Photography Photo Workshop have helped me not only keep my job, but expand my responsibilities.
And I notice that there's a revised second edition out now. Well, I'm getting my parents a new point and shoot this Christmas, might as well get them a copy of this book, too! I'm not giving them mine - I need it.