I could use every adjective in the dictionary to say how good “The Avengers” is. Instead, I’ll go straight to why.
1) The opening sequence. We open with the right characters- Black Widow, Hawkeye, Coulsen. Characters we don’t know and understand as well and need to invest more in. Loki comes right out as what were afraid of, and man, we know he’s deadly.
2) There’s a clock. In the opening and ending fights we know we have two minutes until all hell breaks loose. It isn’t just a matter of who wears down the other.
3) It’s easy to see the humanity in the heroes. Captain America looses the Boy Scout act. For a little while. Mark Ruffalo brings a whole new, unbelievable, empathic side to BOTH Bruce Banner and the Hulk. Both Ruffalo and Hulk get the movies MVPs.
4) It’s funny. You don’t have Robert Downey Jr. without some great quips. It isn’t corny and it doesn’t stop the action, either.
5) Pepper Potts brings out the much needed side of Tony Stark. He’s finally grounded.
6) A beloved character dies. I won’t say who, but right when you think “someone has to die for me to believe any of this and invest myself further” it happens. And you’ll hear gasps, moans, and sniffles.
7) Joss Whedon hangs lanterns on plausibility issues. For example, Loki tells Thor straight up “I can’t believe you keep falling for this” after one of his more used tricks.
8) Tom Hiddleston. I don’t need to elaborate.
9) Great planting of some material early on. Especially Black Widow’s talent for getting information which comes in extremely handy later on.