The game is anything but ergonomic! Bohemia has obviously been saving user tests and that's a shame. Operation Flashpoint was playable, Dragon Rising done well, Arma 3 is much less. Blame it on a plethora of useless options and corresponding function keys: 3 modes of sight and only one would suffice, positions that we forget how to enable the inventory we should close it by clicking the button to look around that give the impression that the character is an owl or has no head. The tassel is in the management of teams: give orders to a bunch of guys at the IQ of an oyster with a complex set of keys which 3/4 are useless and successfully survive is a miracle. An order which in reality would be resolved in a sentence requires a complex sequence of actions that eventually irreparably screwed up as you order types are morons.
As for the AI, it is also stupid, but Bohemia compensated by making the (too) effective: we are left to struggle against superhuman soldiers spot you from behind the bushes and you slaughter the light machine gun while you are hidden behind a wall. Some missions of the single player campaign then turn the repeated sudden death before they find a way to cheat.
Add to that the management of the destruction of the environment far less advanced than on older games, basic sets that are renewed very little (we pass many times in the same empty house), interactions with all the scripted environment , vehicles which give the impression of not having weight and which are impossible to drive as little management is manageable and you have a lack of care in carrying that kills the interest of the game.
Bohemia could have made the ultimate realistic FPS, but they missed the mark.