As far as the standalone Marvel Cinematic Universe movies go, my favorite has always been "Captain America: The First Avenger". I wouldn't necessarily say it was the "best" of the standalone films, that's a judgement that's far more difficult to pass and also a far less interesting discussion (at least for me). But it was always my favorite. It felt like one part "Raiders of the Lost Arc", one part "The Dirty Dozen", and it never once tried to approach its material with irony or self-awareness. On top of that, the cast was great and diverse, the story blended seamlessly into the ever-expanding MCU with references to "Thor" and "Iron Man 2" all over the place, and it was just plain fun. It was unique, it was interesting, it was entertaining, it was bold. I loved it.
Still, I always had to give it the qualifier that it was my favorite standalone MCU movie. Obviously, "Avengers" was always my favorite in the MCU canon. How could it not be? It was smart, it was impressive, and it was indulgent in all the best ways.
So when I say that "Captain America: The Winter Solider" is my favorite MCU movie as well as the best MCU movie to date, I want it acknowledged that I say this without qualifiers. Not only do I enjoy it more than any other MCU movie to date (including "Avengers"), I would argue that it is objectively better than any other MCU movie to date (including "Avengers").
If you care at all about the Marvel Cinematic Universe, you need to see this movie. That is without question. You need to. Plain and simple. Heck, even if you don't care about the MCU, you should probably still see this movie.
That said, I don't think this movie is for everyone. For example, this movie probably wouldn't pass the Pat's Mother Test, that is to say, if my mother would fall asleep while watching it, it fails the test. A good chunk of this movie is action and intrigue and that sort of thing just bores certain people. I don't personally understand why, but some people also dislike chocolate and pizza and some people love Moxie.
If I were to try and describe this movie, I'd probably say it's like a Bourne movie if Jason Bourne fought like Tony Jaa on PCP, carried a shield, was a really good guy, and was friends with superheroes.
The fight scenes are incredible (note: I underlined that shit), the car chase scenes are some of the best I've seen since "Blues Brothers" (coincidentally, one also happens to feature a whole mess of police cars chasing the good guy), the plot is well-crafted and makes internal sense, the dialogue is never pointless and always interesting (and often funny without breaking the tone), and the movie understands the MCU continuity better than any other standalone movie since... well, since "Captain America: The First Avenger".
That's all I'm really willing to say before going into spoiler territory. If the above doesn't interest you, you might not like the movie. If you're looking for a big romance subplot or a straightforward good vs. evil story or a story where problems are solved neatly and without a lot of violence... This isn't your movie. Sorry! That said, if you tend to enjoy action films or spy films or superhero films, you need to see this movie. So go do that and join me for some SPOILERS...