The AA in CW is stronger than previous recent COD's. I did not go back and compare it to BO2 or anything last gen. But compared to BO4 and MW it's definitely stronger.
I tested standing pull, moving pull, bubble and sensitivity. When using lower sensitivities, it's very very strong. If you're playing on 14 (max) sensitivity with 1.0 ADS sensitivity, you're not going to feel it quite as much. If you lower your sensitivity to 12 or below, and use 0.8 or below ADS sensitivity, you'll see what all the fuss is about. It's pretty much an aimbot.
Sniping in CW is a lot harder and requires a lot more practice to master.
Maybe in comparison to MW. But in general, sniping on Cold War is the easiest it's been probably since BO2. The aim assist is incredibly strong, but that's not the issue. CW has bullet magnetism (officially referred to as target assistance). The same tech that Destiny uses. You can test this theory out by intentionally missing by mere inches on static targets, and the games target assistance will complete the work for you. *shrug* I guess if you call that "challenging" lol