God damn. Aside from being a great film it truly is a flawless combination of all of the films that preceded it. The movie shows us that every prior film was a proper stepping stone to this.
Captain America Centered on the Tesseract. Iron Mans suit was a riff on the tesseract tech and gleamed off that. Loki was set up in Thor and comes for the tesseract, we got a flawed Hulk film yet was still salvaged and corrected just right to come into play as well.
The film Avengers worked to take what was there work off of all of that to weave it all even retro actively to make it all worthwhile and meaningful.
I miss When each phase worked to make something that was both cool as a standalone but also satisfyingly party to a bigger whole.
Coulson shows up in every film, an Everyman then becomes a glue in Avengers whose death becomes a galvanizing force that pulls them together ultinatly forming The Avengers. You could even argue they were named that because of him.