By far the best Superhero movie EVER! I'm not saying that because it's made $1billion in 19 days. I'm saying that because of Joss Whedon.
For those not in the know Joss Whedon is the genius behind Toy Story (wrote the Oscar winning script) and Buffy The Vampire Slayer (both the movie AND the series). He wrote the movie and didn't direct it. Because the movie didn't live up to HIS script he created the series. He also wrote Marvel and DC comics (which ones I can't recall). He's a huge FANBOY!
He was on track to write and direct Wonder Woman but Warner Bros. rejected his script so he went to write and direct The Avengers. The reason it works so well is because Joss took liberties to watch Iron Man and Iron Man 2, Thor, and Captain America: The First Avenger AND he possibly viewed The Incredible Hulk late night on cable BUT he also read the comics. After doing all his research THEN he wrote the script. AH-MAH-ZING!
I saw this movie twice in the theaters. Flawless. There isn't anything wrong with the movie EXCEPT for pacing towards the end. One part I thought the movie was going to end cuz it had been TWO HOURS it kept going. I was happy but it just felt longer than it's running time.
His strength in plot and character is matched by the actual dialogue. I will buy this the minute it comes on DVD and I can't wait for the extras.