I hope the expansion would fix some of the long standing realism issues that have been there since OFP, for example:
- Proper weapon magazine/chamber simulation (ie. you can have a round in the gun separate from the magazine attached to it, and you need to pull the hammer if you fire it completely empty)
- Adjustable rifle sights, barrel heating for machine guns, removal of rounds remaining from HUD and replace with more realistic system
- Better vehicle damage system, no total destruction of a car for example no matter how much it is fired at with non-explosive rounds (and no magical everyone-inside-immediately-dies feature even if hit by an explosive)
- Improvements in the weapon systems (FCS for tanks, some improvements in the radar systems and guided weapons)
- Many other things I cannot remember now
Typical fps games have many of these features today, even "arcade" shooters that have better weapon simulation than ArmA 2. They were issues with OFP already, but understandable since the game was otherwise so revolutionary and it would really be the time to fix at least some of them