You know what bothered me about Captain America? Captain America.
This is the absolute worse depiction of him I have ever seen; even the 90's spiderman cartoon did a better job. In the movie he was this big, dumb, goofy guy that looked like he may have some sort of mental handicap. He just had this look on his face this whole time. I didn't feel any of the character from him. The only time he seemed genuine is before he got beefed up. That was actually very well done, but also his smallest part in the movie.
Also (and I know this is a weird nitpick) but for someone who's most memorable quote was, "I don't want to kill anyone", he certainly went out of his way to slaughter an awful lot of people. I mean, I know he's no batman, but come on man... don't say something like that all dramatic-like then do the opposite immediately.
I don't know, maybe I am just spoiled rotten with the Avengers animated movies/show? But the live action movie was just terrible.