All of the films leading up to the Avengers (Ironman 1 &2, Thor, Capt. America) were excellent, and Avengers is the icing on the cake. Hands down the best action/adventure film I’ve ever seen. The character development/interaction is what makes it so good. Most AA films focus entirely on the action. Avengers focuses on the characters. (The Hulk stole the show and is deserving of a reboot after the first two weak movies).
Disney is making a fortune on this film. However, they really don’t deserve any of the credit. This was all in the works long before Disney bought out Marvel Movies.