For the standard long list of names in alphabetical order, this book does it well. Girls and boys names are separated into two separate lists, one making up the first half of the book, the other the last half.
Just about every name has its meaning and origin listed. Along with it are variations of the name. This was particularly helpful and gave some extra naming ideas.
But if you looking for something more inventive or creative, this book is not it. It's just a list of 20,001 names. Don't get me wrong, it does what it does well. But reading a list that long may start to bore you.
I'd recommend getting "Beyond Jennifer & Jason, Madison & Montana" by Linda Rosenkrantz in addition to this book. This book probably has more names, but the "Beyond Jennifer & Jason" book will probably keep you awake, and give you some good ideas. I have both books, and I'm glad I do.