Everything you could ask for in an RTS.
As far as the game itself goes the only complaint I can offer is one that will forever plague the series and that is the bugged like movements of some actions such as storming a castle gate or wall. Troops just tend to be not as responsive during those times, but hey when you're controlling so many things at once with each individual unit trying to act as it's own being... Well you've got a lot of room to forgive and the good points of this game definitely outweigh the bad.
Overall I highly suggest buying it if you have even the slightest inclination towards the RTS platform. It brings everything to the table a person could want out of an RTS. Who doesn't love seeing several calvary units in wedge formation plow through a troop of archers?