I think what I am most pumped about is the fact that for the first time since Shogun and MTW, we will be able to relieve units effectively. It always seemed that in Rome and M2, once a unit was engaged in the melee, that was it. If you attempted to pull it out of the fight to let it rest, you risked loosing more men during the pullout. From what Ive seen in the demo, when multiple units ingage in melee, they all proceed to the action, instead of spreading out into a massive blob with only 10 guys actually engaged like in RtW and M2. This will allow a relief unit to engage and hold back the enemy while the first unit to make contact pulls out, without sustaining massive losses. Also the very nature of forming lines and shooting across distances allows for units to be moved in and out of the main line easily.