I bought this thinking it would be philological in nature, but it turned out to be something else entirely; a history of the spread (and decline in many cases) of the use of major languages throughout history. Traditional philology gets only fleeting mentions. If the author is to be believed, such a thing has never been attempted before.
Hence I was less interested than I had hoped, but that isn't the fault of the author - and I wasn't totally uninterested, either. Parts of the book, mainly those overlapping with pre-existing interests of mine, were fascinating, other parts were a bit of a grind. The basic idea of examining how conventional historical processes (e.g. military, colonial, mercantile, migrational, religious, technological) impact the use, spread and decline of languages did seem interesting and original, particularly the generalising conclusions but, oddly, they come before the detailed exposition they are derived from.
Strongly recommended to history buffs - not so much to anybody else.