Well my view is that its quite simple – Black Powder offers an elegantly simple rules mechanism for the whole 200 year gamut of Horse and Musket warfare, and includes generic 'template' troop stats.
But in applying your own historical knowledge, you can, and are encouraged, to adjust the troop stats, and pick and choose from the wide selection of special rules, to fit the army, battle or campaign characteristics you are trying to recreate within that period.
I would go so far to say, that with its unforgiving attention to the command and control mechanism, BP is the only ruleset that truly delivers the keystone Napoleonic experience – having an army so mobile, compared to the opposition, that it can almost be in two places at the same time, thus allowing you to beat a larger, but slower army by achieving local superiority and taking on one wing at a time. Achieved this just once with BP, but the closest I've ever come in 3 decades of wargaming!
I have met many vociferous critics of BP as a Napoleonic ruleset, and so far they all share 2 characteristics: little or no experience actually playing the game, and, I suspect, no real knowledge of what made this period, and Napoleon's genius, so distinct!