I'm a huge fan of these type of games, and in many aspects ARMA 3 lives up to everything except on three points. My first issue is the overall sound of weapons etc. Pretty bad and underwhelming. But you can live with it because the game play itself is good.
Secondly, the damage done by both 5.56mm and 7.62mm rounds is ridiculously low. It sometimes takes 3-6 direct hits to drop a man, even at point blank. And if you're using a handgun it just took me 9 rounds to stop a soldier at 15 feet. Again, you can live with this. You just need to be aware that you need more ammo than usual.
However, last but not lease, the performance of this game is simply terrible. I'm running the latest in everything, GTX 780 TI in SLI, and i7 4930K 6 core CPU and a shitload of RAM, and it makes no difference. The game only utilizes one core and my GPUs run at 50%.
The funny thing is that during the first (of three) campaigns everything was very smooth, but starting up the second one, the fps drops to 1-3 when performing panning movements with your head. It obviously kills the game as when you try to turn around rapidly for what ever reason everything just freezes and in most cases you get shot.
I'm in contact with BI to let the give their story, but honestly...there's a single thread with over 276 pages of post on this subject, and nothing seems to be solved.
I'm hugely surprised to see that GAMESPOT has given this game an 8...
Until there is a proper fix - STAY AWAY!
It's a shame because otherwise it's a lovely game. :(