Yes, weather is a great feature, and certainly made one wince when a musket heavy army got to defend in the rain.

I do like the reduced visibility, BUT I do think that there is a fault with the game where the attacker can "loose" as it can not find a small remnant of the army. The most memorable one I remember in the series was hiding in the forest on a bridge defence when the attackers could swim. Long story short I "won", and about 500 or so enemy soldiers drowned. Exactly how this should be addressed I am not sure, but I feel that there are better methods than have been used.