If you haven't played the original World In Conflict it posibly would be the best RTS to date. But....
Another stupid thing in this expansion that it's not a standalone update and new missions cannot be played seperately. You have to start the all game all over (doesn't matter you finished it or not) because the game integrates to the original story. Example you play first mission from Soviet side and the second from the Orginal WiC from US side. Well that's not bad if you didn't played that game.
The story is same like first one. Invasion to the US but this time from over side.
There is no point to talk about grafics or sounds or gameplay because it's same as original one. I can't say it's bad. Grafics are amazing , nice visuals, effects and so on.
If you are fan of WiC you should get this for sure, or if you haven't played the first one it's definetely for you because this game is amazing.
I would give to it 9 but since it's just mission expansion it drops to 7