I did not plan to see this movie, because Captain America is not one of my favorite super heroes. I always thought that he was Marvel's imitation of Batman.
To my surprise, Roger Ebert gave this movie a good review. Since I respect his opinions, I decided to see the movie this afternoon.
The movie is indeed pretty good, and I recommend it. I enjoyed it more than "Green Lantern" (which was a disappointment) and as much as "Thor" (which Roger Ebert hated).
The plot is good, and the characters well-played. Sure, there is a lot of action and plenty of explosions, but you won't need a hearing aid after the movie's over.
Good performances by Stanley Tucci and Tommy Lee Jones, but the villain, The Red Skull, was wonderfully played by Hugo Weaving, who also was the villain in The Matrix and Elrond in The Lord of the Rings. I always get Hugo Weaving confused with Sam Neill, another fine actor.
Like in "Thor", Captain America is played by a relatively unknown actor. That doesn't hurt the movie.
Recent super-hero movies tend to have trailers of sequels at the end of the credits. Likewise for "Captain America". If you see the movie, be sure to say until the very end of the credits. Then you will be rewarded with trailed for "The Avengers", starring Captain America, Iron Man, and Thor. That movie comes out in 2012.