I really like Napoleon too. The field battles are among my favorites in the series. I think gunpowder is TW's sweetspot. I don't use many mods in Total War, but I do use Darthmod with Nappy. And it is awesome, the musket fire, smoke and sounds of the battlefield. Darthmod adds gobs of smoke and it is glorious
I find these battles more tactical than most. Terrain features feel more important, maneuver too. Melee combat is formulaic for me, I always do the same basic formation and approach battles in the same way. Napoleon though is more free-form for me on the battlefield. I also love-hate the naval side. I really enjoy the age-of-sail ship types, building navies. The combat's not great, and it has a weak trade node system in my view. But the ships themselves are super cool.
I also really like how replenishment and recruitment are handled, probably my favorite system in the series as it sort of straddles the early systems and later systems and the result is really nice.