The Winter Soldier.
<Spoilers>
I was blown away by this movie! It was everything I hoped for and more.
I enjoyed how it showcased more of Caps abilities than the previous First Avenger and Avengers, such as when they he gets aboard the pirate ship at the beginning and simply takes down almost everyone whilst running past them, it looked brutal and elegant at the same time.
The espionage and intrigue was also great, and I couldn't help but think of Civil War when SHIELD/HYDRA came after him. The cinema I saw it in was full of people who obviously didn't know who The Winter Soldier was, so when his mask came off it was revealed to be Bucky it was met with a unified 'Gasp!' and whisperings of 'OMG! It's his friend! It's Bucky!' something I haven't experienced at the movies in some time.
I also loved Sam and Steve's relationship, it felt great and natural to me, and Anthony Mackie looked fantastic as The Falcon!
4 Stars from, it would be 5 but, for reasons unknown to me, I found Black Widow to be kinda annoying in this one

