This book is about much more than one might assume from its title plus what is written on the back cover. It is true that it does describe the evolution of the French language from long ago to the present day but it also talks about the promotion of the language and its spread, initially in the area of Western Europe that is now France but also globally during the last 300 years.
Most interestingly, it gives a good insight to the use of language to spread influence and cultural ideas. For example, France was devastated by the Second World War but and at the end of that war found its global influence much diminished. However, through the promotion of French the Frence government saw a way of spreading French culture and influence aborad without any hope of doing so in other traditional ways. This policy of using "soft power" has been relatively successful too with French cinema being far more developed than say that of the British, and the Alliance Francaise being an institution much better known than the British Council (which I, as a Brit had not heard of until I read this book).
The book is written in a readable style and does not become involved in detailed discussion of grammar but focuses far more on the bigger picture. Also it is a book written by French-Canadians and is therefore much more global in perspective than "France-centric".