The Army concept is excellent but too much rigid. I tried to list some problems and ideas for Civ4 (maybe some posts have already been published about it) :
* No Armada for sea armies
* No Air fleet for air armies
* Can't upgrade units in armies
can't unload units in the army !
* Must wait a heroe to create armies
Why can't we create armies when we discovered a technology like Military Tactics ? Making them cheaper would allow the ennemy to use armies specialised in defense !
* Units in armies fight one after the other. Could be interresting to use Archers and artillery and at the same time to attack with knights or tanks. For example : Your knight is fighting against an hoplite, at the same time, your archer is bombarding from behind your knight. Thus the hoplite could lose 2Hp in one round. Would improve strategy : archers would be more interesting if they could afford you any victory
I remember CTP had 3 conventionnal units : 1st line units (Warriors, Hoplite...), Artillery (Archers, cannons, catapults...) and flank units (knights, cavalry...). 1st line could attck only if it had an ennemy in front of it, Artillery could attack from behind and wasn't attacked until 1st line and flank units were alive, flank units could attack even if it has no enemy in front of it, it was an extra-attack. In civ4, archer and artillery could attack when an other unit is fighting, fast units could attack artillery and archer while there are "1st line" units.
* First armies should upload only 2 units, then you could upgrade it to 3, 4 and 5 units (or more).
Any other idea ?
* No Armada for sea armies
* No Air fleet for air armies
* Can't upgrade units in armies

* Must wait a heroe to create armies

* Units in armies fight one after the other. Could be interresting to use Archers and artillery and at the same time to attack with knights or tanks. For example : Your knight is fighting against an hoplite, at the same time, your archer is bombarding from behind your knight. Thus the hoplite could lose 2Hp in one round. Would improve strategy : archers would be more interesting if they could afford you any victory

* First armies should upload only 2 units, then you could upgrade it to 3, 4 and 5 units (or more).
Any other idea ?