[Edi]

Mechanics-wise it does compare to CoE2, but more polished, more complex and more transparent. Generally, more everything, I should say.

Unit graphics are a serious upgrade from Dominions for the most part (though some graphics are the same). Some of the graphical improvement comes from the interface, because the same graphic (exact same sprite) displays to much greater effect on the CoE3 interface.

Allied games are the biggest thing and that has had some improvements. For example, there is now an option where defeating a team requires defeating all players on that team before they are all eliminated. Without that, as soon as a player loses all commanders or all citadels, they are gone. Now one player can lose all commanders or all citadels and still stay in the game (and take a new citadel, or wait for new commanders to become available),