Ugh, 3D. I'm not surprised to be honest with you. Once word spread that he wasn't a douche bag smack talking moron (exactly like his comic book counterpart), the movie should be able to do well based on the merits that it is a great film. Also, they would never understand this, but he doesn't stand for anything the modern day US Government would do, like myself. He is a true patriot, a patriot to the ideals of our society, not to the broken US government.
Also, not to nitpick, but what do people think South Korea and Russia are? Neither is actually Communist anymore. Russia adopted a new Constitution in 1993, declaring they are no longer aligned with that particular view of thought, and South Korea isn't Communist at all, it never was since it existed.
But, I digress and recognize that few people pay as much attention to this stuff as I do.
Back OT: I'm not surprised it did well. It was a good film, the direction was great, it was well written and the execution was absolutely perfect. I am surprised in all honesty that there was an expectation of it doing poorly because the character is named Captain America. I would arrive first day to see a Union Jack movie, or a Colossus movie, or even a Black Panther movie. All of these are international super heroes from England, Russia, and Africa (the fictional African nation of Wakanda) respectively.