This book is full of interesting things to read about, but it suffers from the fact that the answers to the questions are only given a superficial amount of research, or are purely speculation. It is fun to read as long as you don't take the answers too seriously, and is in the same vein as the Urban Legend web sites (such as snopes.com) and newspaper columns (such as Ask Cecil) which delve into obscure trivia on everyday things.
This book is purely entertainment, and shouldn't be considered the definitive answer on anything. Also, much of the material is taken from talk shows and reader letters, so reading this book is a lot like being in a chat room or BBS and listening to armchair philosophers expounding their theories.
In all, if you want urban legends, you can use the Internet for that, and the web will be more up-to-date than what's contained in this book, but if you want entertainment, this book isn't half bad.