Well by now it's just silly in how over the top action heavy and dramatic it tries to be. The storyline could be amazing if it went into Red Alert territory and made fun of itself but as it is now, it's just silly. It's badass for the sake of being badass, soldiers are heroes because they have big guns and it's loud and explodes a lot. It's not aimed as a childrens game, but it's basically like manhunt, nobody but 13-year old puberty-heavy teens are really into this kind of silly badassness.
I'm generalizing for the sense of making a statement here, I myself liked playing Call of Duty 4 and Modern Warfare 2 was...alright. World At War was just as over the top and dramatic as 6. It's hard to express it without stealing arguments from Yahtzee for example, but basically it's that. Too badass to be considered serious for anyone but puberty-hitting teens.