The Avengers is popcorn cinema at its best.
I would highly suggest watching Iron Man 2, Thor, and Captain America before seeing The Avengers. The plot is drawn entirely from characters and themes established in those films. There is a great deal of exposition, so it's not necessary, but I do feel like it makes the characters more defined. This is especially true regarding the villain - Loki (superbly played by Tom Hiddleston), Captain America (Chris Evans), and a secondary character I will not reveal in this review. I thought these three established the core of what makes this film successful - a desp*cable bad guy, a true leader, and heart; the reason why they fight.
The Avengers opens with SHIELD and its director, Nick Fury (Sam Jackson), in possession of the Tesseract - an energy generating cube. This object is previously referenced as a source of unlimited power in Thor and Captain America. Loki appears inside SHIELDs secret base, destroys it, and tells Fury that humanity will soon be liberated from the purpose of freedom. Fury believes Loki will use the Tesseract to open a door to another world and bring an alien army through to conquer Earth. Fury revives the Avengers Initiative, a plan to bring together the world's most extraordinary people to battle a crisis of this magnitude. He sends the Black Widow (Scarlet Johannson) to find Dr. Bruce Banner (Mark Ruffalo), Agent Phil Coulson (Clark Gregg) to get Tony Stark (Robert Downey Jr.), and personally appeals to Steve Rogers (Chris Evans) to join the team. Hawkeye (Jeremy Renner) and Thor (Chris Hemsworth) are soon to follow, but you have to see the film to get that detail.
Every character in The Avengers gets their time in the sun. This is an incredible feat of storytelling by Whedon and Zak Penn. The task at hand, saving the world from Loki and the alien horde, is obvious. What makes this film supremely enjoyable is seeing how primary characters from other films, can be so deftly woven into an ensemble piece where each is critical to its success. Tony Stark is hilarious and aptly played by Robert Downey Jr. But he is foremost a genius, and critical thinker, the perfect person to engage Bruce Banner and make him understand how valuable the Hulk is. Loki has lived in Thor's shadow, but despite his adopted brother's criminality, Thor wrestles with the thought of killing him. Hawkeye and Black Widow are not superheroes. Their membership in SHIELD and friendship are forged from years in darker places. Every team needs a true north, a mythic hero for good, who also knows how to fight in actual combat, who better than Captain America? Whedon and Penn flesh out their characters personalities. Then puts them in a situation where their virtues shine. It's entirely believable and perfectly executed in The Avengers.
Fear not action fans, your cup runneth over here. There wasn't a dime wasted in The Avengers on special effects. The film looks magnificent, a comic book come to life. Every fight looks good, but the climactic battle is very impressive. It's akin to the finale of the last Transformers film, but better staged and not as cartoonish. Iron Man and the Hulk are especially awesome opening cans of whoop-ass on alien ships, while Captain America and the other Avengers are more traditional fighters. Anyone with Hulk on their side is going to win the fight. We finally see the green guy unload, and he brings the two liter of whoop-ass to the party.
Every fanboy should tip their head to Joss Whedon in respect if you should ever have the honor of meeting him. Marvel and Paramount did a great job bringing in this director to piece The Avengers story together. His film is so entertaining; I think it cannot be underestimated as an achievement. I realize this is directed to people like me, and if the idea of costumed crusaders seems childish, then The Avengers probably isn't your cup of tea. But anyone who walks into this film with an open mind and willingness to suspend disbelief will have a great time. This is popcorn cinema at its best. I'll be first in line to see it again at midnight Thursday.