I still can't get over how good the Russo's and Evans NAILED the characterization of Cap.
There are three facets of Steve Rogers that have always stood out to me.
1) Fearlessness and swagger on the battlefield.
-Man oh man, did they get this part right. If the Avengers had just one flaw (my second favorite movie of all time), its that Cap wasn't the super-soldier we wanted. While it was understandable, as he just got defrosted and was facing strong personalities like Stark and Fury, he seemed rather timid and meek at times. He was certainly fearless and heroic, but didn't have that confidence or swagger yet. I believe he was still "warming up".
But in TWS, we see the "real" Cap. That sequence on the Lemurian Star is a clear example of exactly what I mean. Obviously he's more comfortable now, and his swagger and confidence is high. The way he fights flawlessly, seeming to enjoy the rush while always having the goal (saving the hostages) at the forefront. THIS is the Captain America I have always seen in the comics.
In a film chock full of awesome examples, I thought the Cap vs Quinjet scene also captured it excellently. The way he doesn't back down or hesitate when the Quinjet and barrier are in the way, but rather speeds up, screams of confidence in his abilities. That was simply a masterful sequence.
2) Leadership.
-Again, while he deserves some slack after being thrust into the Avengers upon waking up, he did not seem to fully accept his leadership position (although he flashed shades of it throughout the movie) until the Battle of New York. In TWS, Cap has clearly grown into the role and has embraced it fully. He's no longer timid or uncomfortable. From laying out orders for the SHIELD strike team on the Lemurian Star, to challenging Fury on BW's separate mission and on Project Insight, to the rallying speech at the end. They nailed it. Sam was another piece of the puzzle, as his willingness to follow Cap into anything is a testament to his leadership.
3) "Skinny-Steve"
-This may be perhaps the most overlooked aspect of Captain America, but it's one that I find very important. In all the action, leadership, and confidence, it would have been too easy for Evans to lose the "skinny-steve" in the "Super-soldier".
But I was extremely pleased that despite the high octane nature of the film, they managed to show glimpses of "skinny-steve". And I'm not talking about the flashbacks. I loved how they included the earnest and simple nature of Cap, as this was important to me. They definitely honored Dr. Erskine's wish of Cap not becoming a great soldier, but staying a good man.
Despite his growth as a character, the kiss with Natasha really showed how underneath all the "Super-soldier", Steve is still a really simple, sincere guy. Evan's delivery of the "Yes, they do." line in response to Natasha's quip about PDAs making people uncomfortable, and his "That isn't exactly the word I would use." line after were so perfect because I could see "skinny-steve" saying the same exact thing, in the same exact manner. It's refreshing to know he's still the same guy underneath.
His "If I run in these shoes, they'll fall off." line and "And we're borrowing, take your feet off the dash." was perfectly executed too. That one line displayed that while he can do things like steal cars easily, he'll never do it. Even when he did, he made sure he was only "borrowing".
These people get Captain America, and I'm ecstatic that they'll be returning for Cap 3.