Haven't had much time to play with it, but in besieging Nottingham ran into three bugs already:

1. Routing peasants on the wall above the gateway were stuck there, and no matter what I did I couldn't get any units into the gateway to attack them. So the gateway stayed Saxon, permanently (good thing they don't have the boiling oil that RTW did). Couldn't even shoot them from the ground with archers. Or was this because I had destroyed the towers? Does that trap units in the gateway? Maybe this isn't a bug...

2. My cavalry, inside the walls, was sent to take the unguarded center square. Instead, they marched out of the castle and parked themselves outside the walls.

3. Double click to Run is still broken, like it was in Alexander. I have to make the unit walk, then hit R to turn it into a run.