1. There are many changes and lots of new things. Lots of people like to think of MM as a temporary long-lasted beta version of the current DLC.
2. As said, the DLC brings lots of new features; New classes, new arsenal of weapons, very nice looking and well polished uniforms, awesome environment with awesome maps, etc etc.
My tip for you would be that you should keep an eye on the Taleworlds forum, Napoleonic Wars section. Lots of community members post threads regarding the game. It is hard for me to answer your question when I lack the information such as what your main interests are regarding the new release.
nw_drako
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