Got a game of Grande Armee in over Easter. We refought Talavera, very doable in this scale as are all the big battles of the Naploeonic wars.
I took the British and Spanish. The French came at my British left flank and ignored the Spanish. I extended my flank to meet them, but had strong units on the ridge. This is a battlefield I have visited so I could picture the terrain. My recollection was that it was much more rugged than the scenario, but we got to the same point of decision as in the actual battle.
Somewhat disconcertingly my veteran British line collapsed and I was struggling to plug the gaps with cavalry while they rallied. In fairness to the scenario my dice throwing was abysmal. None the less I think it is important that the effectiveness of British volleys is reflected better in the strength points in the scenario. There are few variable factors in the rules to keep it simple, so the British advantage needs to be reflected in strength points.
This picture shows the point of near disaster.
The rally rules are a particular feature of Grande Armee and certainly saved my bacon. The cavalry held up the French and my line brigades rallied and held the line.
Despite some faults with the scenario, I think the rules are still good for big battles in 15mm.