Looks great. A few items I've always wanted to see:
1) When you join a battle that is already raging, I'd love to see the battle already raging. The two sides should already be engaged, with my forces moving in to join the combat, and maybe getting a tactical advantage against the enemy. It would add some intensity for larger battles, with a sense that I'm interacting with a dynamic, complex world, not a battle generator that is waiting for my input.
2) Roads. I'd love to see roads that affect army movement speed, providing common pathways for merchants and armies alike. This could make for realistic checkpoints along roads and add a much more detailed tactical experience to the campaign. A village along a major thoroughfare could be a huge asset for trade or fortification alike.
3) Politics, Diplomacy, and Rebellion. It would be great to see further development of the internal and external politics for each faction, with rebellions springing up, powerful families opposing their king, etc.
4) More tactical depth in combat. Having more control over troops, in a realistic way, would be great. Training followers to be sub-commanders, setting tactics for squads before battle, etc. The tactical depth really adds to the immersion.