The original Captain America movie was always a bit different from the other Marvel superhero movies in that it took place in the past, in a period where he could be presented with complete sincerity and not look utterly ridiculous, but his shift to the present posed the problem of how to do that in the modern day. The Winter Soldier found a pretty good answer: fit him into the center of a conspiracy reaching back to the groundwork built in the original movie and cut him off from all his resources, without trying to make some cheap allegorical shots at present day politics.
The end results is fascinating, feeling like a cold war era spy movie (captures that paranoia quite well) that somehow happens to take place in the presence and which has Captain America in it and manages not to look stupid. Also lots of action. It’s fun how the Captain America movies are better movies on their own than both Iron Man and Thor, which is something I would have never expected.