incredible (and i mean incredible) action, sharp and funny dialogue, perfectly paced, the entire cast had chemistry and everyone had their awesome moments, and that entire final act had me gushing like a fangirl having multiple fangasms
and I'm not that big an Avengers fan!
certainly there were stuff that could be better like Scarlett Johansson's bland portrayal of Black Widow, Tony Stark having the only real character arc, and Thor being relegated to a mere powerhouse while not really giving off that godly aura
and it lacked... gravitas
still, Whedon pulled off a fantastic job directing and writing the movie that could have very well fallen apart trying to balance all those elements
it's an amazing jaw-dropping spectacle and one of the best superhero and action movies
better than all of the Marvel movies except for Spider-Man 2 and Iron Man
Batman Begins is also better and The Dark Knight is still king
those four movies had that gravitas the Avengers lacks
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all you need