Of the 15 films that belong to the Marvel Cinematic Universe (MCU) to date, this has to be a contender for best film (probably along with Iron Man 1 and the sequel to this one 'Civil War'). There are several set pieces which are absolutely some of the best sequences in any Action film, ever.
The opening sequence aboard the ship shows Cap at his best, tearing along the deck of The Lemurian Star taking down all of the terrorists pretty much single-handed using only his shield and martial ability. This is finally the Captain America that we know and love from the comics, the Ultimate Warrior. One of the things I thought would be a big issue in bringing Captain America to the big screen would be the use of his shield, but once more Marvel have conquered that challenge ably and we see Cap using his shield to great effect throughout. Even Spider-Man chimes in during his excellent battle with Cap in Civil War with a "Wow! This thing really does defy the laws of physics!". There's also the attack on Nick Fury in broad daylight. The elevator fight scene (again in my opinion is one of the best choreographed fight scenes that I can think of in modern times). Equalled only by Daredevil and The Punisher's escape from the headquarters of The Dogs of Hell (Season 2, Episode 3 - New York's Finest), and that's just the first half of the film!
Add to that, the fact that this film has an excellent plot and is much a drama as it is an Action film, which means that it's almost two and a quarter hour running time flies by as you are in turn engaged by the superheroics and the story that is being told.
At heart though, 'Winter Soldier' is a political thriller wrapped in a summer blockbuster that tries to tackle the thorny issue of government surveillance and accountability in the times of the 'War on Terror'; the all consuming internet, 'topped-off' by the increasingly pervasive nature of the plethora of digital data that we all have out there now. How many times have politicians trotted out the: "If you've got nothing to hide, you have nothing to fear" line in response to arguments for greater power to surveil 'us' — the people they 'supposedly' serve.
Everybody has 'something' to hide, right?
It's good to see Marvel punching up the story quotient on the films that their producing. One of the things that a two hour film struggles to do that a multi-installment story in a comic does so well, is tell a fully rounded story. But Winter Soldier, makes a pretty good fist of it.