While its true that most offices have gone casual these days, this is a book that should still be in every gentleman's library. To be without this knowledge is to be at a grave disadvantage -- Even if your intent is to break the rules, you'll need to understand them first.
The great thing about this book is that it covers the history, origin and derivation of classic men's style, allowing the reader to not only understand the grand traditions, but to approach modern style with a new awareness (read: power) and appreciation.
I absolutely loved this book -- In fact, I wish I'd read it before I ever entered the business world, as it certainly would have saved me a great deal of time and money, not to mention an awkward wardrobe of costly and seldom-worn garments.
If you're interested not only in what to wear and how to wear it, but curious as to where it came from in the first place, this is the book for you.