First and foremost, "Captain America: The Winter Soldier" is the best action film out of the entire Marvel movie universe so far, bar none. Just in terms of sheer impact and choreography and execution and clarity of geography and did I mention impact because DAMN. If that is all that this film did well, that would be enough for me to recommend it.
Beyond that, though, "Captain America: The Winter Soldier" is a tremendous piece of pop entertainment, smart and engaging and featuring a home run movie star lead performance by Chris Evans and the best overall supporting cast in one of the Marvel movies in terms of everybody having something significant to do and everyone being written for to a degree where they're playing people and not just types. Written by Christopher Markus & Stephen McFeely, this movie hits the ground running, literally, in a great scene where Steve Rogers (Evans) meets Sam Wilson (Anthony Mackie), a former member of a para-rescue unit who now works at the VA hospital. In one quick moment, they dispense with any need for fish out of water jokes and they introduce the notion that Steve is struggling with the bigger issues that affect him as a man out of time. He is having his doubts about the work he does for S.H.I.E.L.D., and in the film's first big set-piece, we see just how wet that work actually is.