It's a film which could have gone badly wrong, and come across as a film which was overly patriotic, cheesy and worse of all tried to pass itself off as serious.
But it wasn't, they handled a difficult subject matter well. This was done by making it more about the Captain being a "good person" rather than the nation he symbolises as being good. Captain America doesn't actually represent America as "good", but he represents a good American, which is fine, anyone can relate to that.
I liked how also America's allies were given "diplomatic" treatment. Captain America rescued them from captivity, and then they later on in the film "rescued" the Captain. Basically, it's team work- Captain America relies on his allies, and his allies relay on Captain America, and that's the metaphor that people outside America want when looking back on WW2- not the America saves the world single-handedly lark, which was parodied in "Team America".
I'm slightly worried however that Hollywood feared this film wouldn't sell abroad because they worried it was overly-patriotic. This suggests that Hollywood doesn't know it's international audience all that well since it doesn't know what non-American audiences like and don't like. You'd have thought with all the international talent in Hollywood they'd have some idea as to what the outside world likes and doesn't like.