I agree with Dowly. Especially the performance was, after I found out how to get my second X1950Pro to perform properly, a pleasant surprise. I was hosting the MP campaign, the mission was set at night and I was frapsing here and there, and it was still playable at my end with settings at normal/low. NVGs look really really good, and the word is much more live than that of A1. Lot's of trees and bushes, grass all over the place, goats and sheep...
Arma1 would easily bring my PC to its knees with that kind of detail, so the engine has definitely been optimized.