Heavy-duty, well-researched, military history. Definitely not for everyone, but I agree with folks who consider this a must read for that unique collection of "enlightened" academics who focus their research and teaching on the art of war. Having said that, this historical vignette is much less of a how to guide or handy reference for planning an assault or defending valuable terrain ... and instead chronicles the transition from a feudal/royal monopoly over the arms-bearing "arts" to the more modern (dare I say, familiar?) profession of citizen soldiers, selected on merit, educated (not only in combat-related skills, but ... critical thinking and problem solving), led - in battle - by a meritocracy rather than the worst byproduct of a monarchy: ever-diminishing, arrogant, insular, ill-prepared, and closed-minded bloodlines.
As fascinating as this (admittedly small) slice of history is, one can excuse a cynic for deeming this historical nugget largely irrelevant today. Particularly in the U.S., the military officer corps are populated with a broad cross-section of the nation's youth, educated through service academies (at West Point, Annapolis, Colorado Springs, ... and, if you wish to be inclusive, Nassau) or innumerable public and private colleges and universities, through the services' reserve office training corps (or ROTC) programs. Subsequently, these officers, upon commissioning, attend extensive "Basic" classes (multi-month professional education immersions) and, throughout their careers, return to classrooms for (year-long ... or longer) "Advanced" courses, Command and General Staff College, War College, and the like. Read the biographies of today's military leaders, and, in addition to their undergraduate degrees, most have masters degrees, and many boast PhD's. We've come a long way from a military leadership dominated by royal offspring that not only rejected formal education but feared it as a risk to the status quo.
At another level, the book is interesting as a snapshot into the low point of the Prussian military (defeat and despair at the hands of Napoleon) and its subsequent rebirth, ascendance, and sustained dominance (only after turning the table on Napoleon). And, of course, it also serves as a biography of sorts of Scharnhorst, a fascinating character on a number of levels.
But the book's title fairly implies that, in addition to Scharnhorst, it was the assemblage of enlightened soldiers through the Militarische Gesellschaft or voluntary "military society" or "military Sorbonne," that upended the stagnant Prussian military and paved the way for a modern, effective, innovative military. This is pretty interesting stuff if you're interested in professional societies or professions, generally, or ... of course, the creation and evolution of academic or learned disciplines.
Full disclosure: the book was White's graduate student work - and, while it admirably achieved its purpose there, it isn't written in the style or with the fluidity of popular military history books, and its stated length is deceptive, given the extensive number of substantive footnotes, appendices, and the index. In other words, it's heavy going (maybe even a bit of a slog), but, frankly, it's a very slender volume (in terms of the total amount of reading involved, particularly given the return on investment).