The friendship of Captain America & The Falcon which began back in the comics of the 1970's is one of the best things of The Winter Soldier movie. These two genuinely like each other and respect each other's abilities. In the movie, Sam Wilson- in a way, helps Cap adjust to living in the 21st Century. He explains things like smartphones but at the same time- He shares a camaraderie with Cap because they are both soldiers. They've both seen combat and the horrors of war and they share that bond. They are both War Horses.
As the movie progresses Falcon explains to Cap that Bucky- The Winter Soldier, may not be someone that Cap can save but he will have to stop him. This is a choice that Cap will have to make. Is Bucky lost to him forever and have to be put down? or is their some glimmer of Cap's old friend still there? This is really a story of two friendships for Cap/Steve Rogers. His old friend from WWII who was Steve's friend way before the Super Soldier Serum transformed him- and his new friend, here in the present who is helping him adjust to a strange new world of high tech gadgets and ambiguous morality.
Telling the Good guys from the Bad becomes the central theme of this movie. There are no black & white absolutes in this world but rather a huge gray area. This is something Cap cannot tolerate or be a part of. When it becomes clear who the real enemies are, Cap makes people see that they have a choice: To stand up for what is right or join the very forces that Cap fought against in World War Two.
Cap knows he can rely on the Falcon & Black Widow, but the odds are seriously stacked against them.
I hope they continue with the Falcon and introduce him into the Avengers- as they did in the comics of the late 70's. Marvel would be foolish not to. The dynamic between him and Cap is genuine.