Been looking forward to this for a bit - a tryout of the "Principles of War" Napoleonic rules at the club, courtesy of G.
As it was a tryout, and neither of the two of us running the French knew the rules, we went for a fairly classic and simple set up - the opposition were a mix of British and Portuguese set up on the side of a hill (one assumes, traditionally, in the pouring rain where two maps join). The conventional approach was adopted - wind up the infantry in column of attack, point at brow of hill, support with artillery and light cavalry, and leave the heavy cavalry off to one side to lend tone to the otherwise vulgar brawl.
Things went much as expected: the cavalry on the French left disappeared in a huge cloud of hooves and dust to meet with their Allied counterparts, and the French infantry weathered a storm of withering fire from the line of British (who were unlucky to be shaken twice at speculative long range by a gun battery I really should have moved closer) and Portuguese.
As expected? It boiled down to 'will the French break before they make contact?' Luckily for R and I, they didn't, and the upshot was that one line of Portuguese fell back, shaken, as did one slightly over-keen unit of artillery, and the column followed through onto the British line.
On the whole? Great set of rules that didn't get in the way - some of the mechanics were interestingly different, with a bit of the feel to Blitzkrieg Commander about the orders/actions allocation.
But ultimately? They felt right. Units did what I expected they would do in a given situation, and the only flaws in the game were really due to R and I not fully absorbing the rules beforehand. And we didn't really need that loitering unit of light dragoons, as it turned out. :D