I had a chance to check out Company of Heroes today at their little theater they had set up. The preview they showed in the theater is a more indepth version of the trailer(like 10 minutes long) full of voices, cussing, and life.
Even with the game in it's alpha state, the engine displayed a near-realistic sense of battle. Everything around is blowing up and people were getting shot up. Mortar rounds scars the battlefield with craters. Almost everything in the environment can be destroyed or damage. Cover doesn't last too long under direct fire. A piano that was once used as cover got shot apart. Buildings as well are also destructable.
The preview also shows the realism on the battleground. Soldiers will take cover behind anything they can find. Wounded soldiers will lay on the ground and try to call for help.
The physics engine helps to give a realistic feel to the game. I noticed soldiers killed by an explosion is given a ragdoll death where the body is launched from an explosion. Debris flys in a realistic manner as a tank shell hits a nearby garrsioned cafe.
The game isn't perfect at the moment. I noticed a few interesting bugs and oddities that occured. However, the game has a good amount of development to shape it the way it's suppose to be.