Haven't really touched ETW since the latest patch, which made the game really more enjoyable. But still, there's one thing that literally gets on my nerves:
Researching Fire by Rank brings you a nice firing drill for your troops but looks really like crap. Not because its unhistorical, but because nearly all men fire their muskets at the same moment. Makes its sound like one big gun thats fired instead of many little muskets.

I know, it has to be a minor thing, since I saw my troops firing not that perfect, too (only when Shader 2 was activated). Now, has this bug been fixed? It's (hopefully) no big deal, but adds a lot of atmosphere to the battles.