Game changing (at least for about 10 years)

Rating: 10/10 (10 April 2019)

Even if the movie, the story, wasn't that great, this movie changed cinema (for better or worse), creating a path to serialized "event" movies, all "important" to have the whole picture of the insane 23 movies arc of the Avengers. Without this movie being this fun, well paced and put together, we wouldn't have the MCU.
And it pretty much delivered on what it promised. Without the need to introduce the main characters, the movie ditched the typical structure and started with a bang to never slow down, really. With action from the start, connecting every single character already presented (the six heroes, their recruiter, the villain). The movie assumed we all knew the characters because we saw the other movies (making them literally a "must watch" to savior all the details and enhance the experience), which was the best decision ever. They didn't follow the rules (they created their own, which will be become stalled later) and made the best possible ensemble movie.
But it wasn't just pure action, because with Tony Stark and Steve Rogers, they started (and would continue in the next movies) their philosophical (lightly philosophical, but still) exploration of war against an exterior threat. And they still managed to give the others moments to shine (if not really arcs of their own). Thor and Hulk with their powers; Black Widow's smart spy mind; Fury's uniting the team, etc.
The action is insane and the CGI ridiculously perfect. Loki is perfect for a first villain and the dialogue is funny with the needed exposition done well.
Having said all that, the second act could be better and parts a bit too childish or just stupid (Loki vs. Hulk; Hulk "I'm always angry"; Hulk vs. Thor). But ultra minor things. Amazing movie.