I personally love this game. It is a great example of an RTS (real-time strategy) game. However, it realistically shows what modern warfare is like. It contains realistic violence, with dead infantry falling to the ground in a true-to-life manner (not rag-dolling) and the bodys linger on the scene of battle for a good couple minutes before fading. There is blood in the game and, depending on the performance of your PC, there will be blood stains on the ground, not overly noticeable, but there.
A plus tho, is that unlike a lot of war games, it doesn't glorify war, making it seem like and admirable and good thing. Rather, a few of the characters try to escape the brutality of the combat and are noticeably scared. World in Conflict displays war as it is; a brutal, horrific, unforgiving scene where people fight to kill other people.
If you are mature, however, this is a very good RTS that will keep you thinking and on the tip-of your toes.