I played some AH2 last night. It's good fun, but I still don't notice anything remarkably different about the gunnery. Some things in the game itself have changed, like the inability to see hit sprites when a plane is under your nose and out of sight. That doesn't necessarily make gunnery more difficult, but you do have to adjust to it.
I expect that most players, after a brief period of getting used to the gameplay and flight model differences in AH2, will find that their hit percentages mirror those in AH1.
-- Todd/Leviathn