I was able to enjoy it as a stand-alone movie. I know a lot of people are saying "What about the other Avengers? What about Shield?" I thought about it, but it didn't bother me that much. I wanted to see how Tony was going to use his wits to handle this seemingly unbeatable bad guy.
I think this will be a problem for all future Marvel movies. The Avengers set the bar sooo high, that expectations are crazy.