Bowden's work is for those who care deeply about the Order of Battle for the three armies that fought at the great Battle of Waterloo on June 18, 1815, as well as for the overall force structures that participated in this much studied campaign. Thus, one can find the unit strengths, unit designations, and even officer names of Napoleon's Army of the North, Wellington's Anglo-Allied Army, and Blucher's (sp?) Army of the Rhine. Each infantry unit is presented as regiments/battalions, cavalry regiments, and artillery batteries.

In some cases, unit notes are supplied giving some reference to specific actions within the campaign, nicknames, or historical background or battle honors during the Napoleonic Wars (especially the French).

Besides data and factoids, Bowden does give an overview of each army, so there is some text besides lists of each army's units. (Here, I think that Bowden is at his most interesting and provocative. For example, he gives his take on the leaders that Napoleon had available to him by which he could "staff" his army. 
Book includes some extraordinary maps displaying combatants' positions for Waterloo as well as the other well-known battles of this campaign: Ligny, Quatres Bras, and Wavre.