As a veteran and big fan of all the galciv games so far, i am eager to play galciv3 as well.
The one attribute which has always escaped Galciv games that i have also mentioned in previous game forums is 'reaction moves'.
Reaction moves are moves that units can make in response to the actions of the current player whose turn it is. For example, an enemy fleet on 'overwatch' set to respond when one of your fleets gets too close. When you trigger the overwatch response, your fleet is immediately halted then the enemy fleet gets to move within the limits of its 'AP' (overwatch action points), usually by rushing out and attacking you, or even to retreat, the possibilities are vast.