Entertaining from start to finish, filled with good and sometimes great action, and probably way too many fanservice (the entire airport scene), this movie doesn't get to the Winter Soldier level, but it tries to stay as close as possible.

The use of the humor is satisfactory, put in the right places without destroying characters or moments for cheap laughs. It also deals very well with even more characters than The Avengers, letting (almost) all of them to be important to the plot one way or the other.

In the end, maybe character motivations and themes aren't as coherent as it seems if you think too much about it, but still, as a comic book movie, the only really important sin is having a very bad villain (almost unnecessary, really). Other than that, pretty good.