Watched this on Wednesday. Really enjoyed.
There is one thing in particular I observed in this that Iron Man 2 and Hulk did not have. The character evolved for the better. Don't get me wrong, it's not that Iron Man 2 or Hulk did something wrong, just that it was refreshing to see a character get built up rather then dismantled.
Just to clarify: In Iron Man 2, Tony is dealing with so many things ranging from the publicity of being Iron Man, down to his own personal failings. This degrades the character over time.
In the hulk, Bruce is constantly on the run, and just when he thinks he has found away to rid himself of the hulk, he has to make a sacrifice and remain on the run again.
In Thor, however, Thor actually starts off as a somewhat repugnant personality, but through his punishment he atones for his brashness and matures as a character, leading to a much more positive flow to the characters development.
And yeah, let's hope Cap. America lives up to the other avengers début.