The Wordwatcher's Guide to Good Writing and Grammar

What makes The Wordwatcher's Guide to Good Writing & Grammar different from other books on the English language? And why the need for another such undertaking?
This book is not a text. Nor is it a collection of fiats or a listing of grammatical rules. Instead, the Guide presents actual problems bothersome to those concerned with the intricacies and nuances of good writing and grammar. To resolve these problems, the book offers guidelines that are currently being observed by the most competent and careful users of the language.
Although the principles of standard, or formal, usage are recommended, equal time has been given to the informal, which makes the decision which to use yours alone.