In a nutshell: a must-see

Rating: 10/10 (24 August 2015)

This movie is frankly excellent. Watching it for the first time up until the fifth time (which for me was after Winter Soldier came out) was very very thrilling. To had a plot, first of all; one that might not show itself well the first time around, but is there nonetheless.
No character doesn't *need* to be present, and no character is out of place. Stark is there because of his father's affiliations with the Tesseract-goings-on, and later his new tower becomes the location of Loki's space-bridge-machine, because of his new energy that he created in Iron Man 2. Cap is there because, well, the Tesseract is the subject of the film's conflict. He is neither cannon fodder nor useless - sure, his action sequences in this movie aren't outstanding like they are amazingly in CA:WS, but since that movie existed afterwards, it doesn't matter. Thor is there because his brother is the antagonist; he in fact has more reason to be in the circle of protagonists more than the other Avengers. Banner is present because he was needed to locate the Tesseract when it was stolen (plain and simple), Barton because, well, he was a Shield agent at the first facility we see, overtaken by Loki's scepter, then et cetera. And Romanoff because, well, she's a major Shield agent who is an elite fighter, as well as the only female of the team.
As for the biggest plot-complaints I have seen: The reason Loki wanted to be captured on the Helicarrier is so that he could disturb the harmony of the team and "set off" Hulk, knowing also that with his teleport-trick he'd be able to Lure Thor and escape... and lastly the reason Banner in New York, after arriving by motorcycle, is able to immediately turn into the Hulk, is because of the ability that is evident at the very end of Incredible Hulk; him being able to voluntarily become angry. No single Avenger dominates the plot. This movie has clever transitions when each Avenger is first seen, has no ex-machinas, no over-abundance of jokes, absolutely no lack of clever lines and dialogue (I refer mainly to Loki w/ Fury), no lack of six-vs-aliens action, great acting, and a sensible ending. Whedon's direction/directing of this film is more than "meh pretty good" - and this movie was only overrated when its fan-hype was still alive. It doesn't "become more mediocre of a film" once more thrilling MCU installments have come out.