In Halo CE there was always some stickiness/follow/lead. If was aiming over a wall it would go at normal speed but as it went over an enemy it would "stick" and :"follow" and enemy a bit.now aiming is the same everywhere.
I play on 10 (which still feels slow) and am used to getting a bit of sticky on enemies but my briefly play today aiming was the same everywhere.
I'm so used to snapping around with pistol and getting a shot thanks to some aim assistance, now it seems the game makes no difference to my aiming between at a wall and a grunt.
edit: snap shots, such as where you spin around and it can snap a shot with the pistol. Every weapon but the rocket launcher and sniper rifle had this originally.