The strategy of having most of the heroes star in the their own movies first and then come together in this one was the right one. This way, you are not wasting half of this movie establishing who Iron Man, Thor, Captain America, Black Widow, the Hulk and Nick Fury are. You can pretty much hit the ground running.
Love this bit:
"Big man in a suit of armor. Without the armor, what are you?"
"Playboy, genius, billionaire..."
😀