I've played before, and I wasn't impressed. Sure, you get new options and abilities, but much of the old, good stuff is either gone, demoted, or destroyed. You have the same general problem with rials in Civ3, but aircraft do the job of helping the attacker. The other thing is that you can split up your effort into several cities and thin out the defenders very quickly, instead of giving them one place to concentrate their counterattacks.