For some apparently the answer is absolutely nothing. But if you bought into the Marvel Universe thing, then you know how they roll. It doesn't mean the movies are all the same. Quite the opposite, as Dr. Strange showed us. But even here you get political statements. And if it didn't do that the movie probably would have been seen as just another Comic Book movie that didn't take it's role model position to also have a message for the viewers.

But do not despair, there is plenty of action in there. It's just that the movie does try to make you think about things and challenge you a bit. Also it does want to show that there are consequences to actions taken. Whether you agree with that approach or not is up to you. And again, there is enough action and fun to be had. You can take anything apart if you really want to and make it look bad, but you would take away a lot of fun that you can have.