Best tactical shooter ever, period!
At first you might just notice the short comings and not the potential, but if you overcome this then you will not just have a game to play until the next big thing but a long term 'partner' for the next 10+ years.
No matter how much you try, there is no game that is comparable to this. If you find the COD and BF series too fast paced, unrealistic, small, lacking scope or just unambitious then ArmA might be for you.
A big 9 and not a 10, since there are still missing elements in the release version that is just not good enough. But as everyone in this community knows, this will be addressed along the way.