Control mechanics
Smoother and more fluid controls but keep them realistic, no bunny hopping or speed vaulting. Current arma 2 control mechanics are unrealistic, jaggy, rough and badly under developed.
Gunplay mechanics
Make it as complicated and realistic as possible while keeping it fun. The current mechanics in arma 2 are terribly cluncky and shaky (no other words to describe it) and as far from realism they can be. Except for reloading times, that is what i like no sleight of hand bs.