I did struggle with aim a little in KZ2, but since then i think i have improved alot. I am perfect in Black ops, but in games like MAG i am always just a little off when it matters which is frustrating.
One thing i have noticed is in most the gameplay videos whoever is playing always seems to have issues aiming, especially vertically - and after sliding. I am starting to think i should get it on PC instead, but this might require an upgrade because i barely scrape the min spec 