Emergent factions (Teutons, William Wallace, New Spain) are also cool.
For me the best bit is the music, because you get Kingdoms stuff popping up here and there.
It also adds mercenaries, a few new units (Men at arms, 'Tanks of their time', as it says in a history book of mine, are the main ones, with two variations), changes most of the faction names to their own tounge, adds reigons, etc.