In my opinion, I think the new one sucks ass compared to the old one. The new one appears smaller on the screen, and in COD4 it takes up the whole screen almost and zooms (magnifies) in a little bit- which is a big reason for why I love it. The newer one has more markings, but it doesn't take up much of the screen, and it doesn't zoom in. I love the old one. They should add that one in as another attachment.
I never used the ACOG for CoD4, I used it on the Intervention so I could do challenges for it in MW2 and the first time I used it I nuked. I did it on Wasteland and I've never used it since.
Anyone who used to be part of the well known SLs back in the day loved the old ACOG, the feel of it was amazing. This one is worse than looking through your Mum's- actually I'm gonna stop there
Theres 2 ways to go about this cuz the ACOG on cod4 is bigger when ya look through it but the mw2 ACOG as a smaller center so when u aim at someone u can seem them clearer