What it comes down to is: break rules and be your own fashion icon. A quote from Sophie Caroline de Margerie in the New York Times sums it up nicely: "She’s very clever because she knows the key to being beautiful is self-confidence."
What's more: only seventy of the 239 pages are on style. The rest of the book is a shopping guide to Paris. At that it seems excellent - you might want to check it out when you go to Paris. But it's not what you expect when you want a style guide.