Mount & Blade Warband: Napoleonic Wars should be an official version of the musket mod that have been overly popular in M&B community. I have tried the mod but it's not my thing. Don't think I'll be getting the official DLC. I suppose those who like the musket mod would love this.
I have been playing Mount & Blade: Warband since it came out - almost exquisitely in multiplayer. I love that game.
Bought M&B: With Fire and Sword a few days ago. I don't like it that much. The multiplayer maps seem to have rather plain and bland design. And since the setting is in 17th Century, there are muskets everywhere. Which removes the combat variety that M&B: Warband has. However, there's a new game mode where the players are commanding squads of AI controlled troops. The mode has versions for Team Deathmatch, Co-op (against waves of AI troops - invasion type of game mode), and Battle version, if I'm not mistaken. That a great addition but I believe it would have been better in Warband.