We have the official announce complete with screenshots planned for next week, but i can give you some info now
This new title in the series will focus on the Teutonic Order in the 13th century, namely conquering the pagan Prussia. The player will act as a Komtur of the Teutonic Order and face historically accurate problems like low manpower of the Order and strong resistance of the heathens.
The biggest improvement IMO is the
strategic mode played in real-time with RPG elements thrown in, first time in the series! You'll be able to train troops, send them across the map to conquer new territories, castles and settlements, etc. - the usual 'grand strategy' stuff.