A great expansion to an already great game
The game itself is great with incredible gameplay and stunning graphics (though it does have a crashing problem on extremely high settings). The use of the essence engine allows for destructible cover/environments and great physics as reflected in another of Relic's games Warhammer 40000 Dawn of War 2. The sound is great with unit responses based on orders you give to them. Plus the creation of a mod studio created by a user under the name of Corsix allows anyone to modify the game to their liking whether they are seeking to make it more realistic, increase population cap for larger battles, want to make a machinima using the game, or just want to mess around and have fun (pistol that blows up tanks for example).
Ultimately a great game that allows for much customizability if you have the time and patience to do so.