This movie is probably the "Star Wars" or "Indiana Jones" or "Lord of the Rings" from the 2010's. It has everything you could want from a movie ... a great story, over the top but solid action, great acting and CGI, social commentary, a sexy female and bad ass males, catchlines and memorable/awesome scenes. Also each of the heroes has it's own momentS to shine and they all gain equal attention.
You do not have to be a comicbook - geek to enjoy this movie but if you are then this movie won't disappoint you. Everything about this movie just makes sense ... even the smallest of details. The only thing you probably should do is watch the 2 "Iron Man", the "Captain America" and the "Thor" movie released prior to this movie. A lot of the background story from this movie is connected to the movies I just summed up.
To finish this review ... this movie is an instant classic and a land mark in the superhero - genre.