The fact that Joss Whedon was able to salvage some sort of coherent film out of all he was forced to cram into a single movie is quite commendable. But the sad fact is that Avengers: Age of Ultron is really just a run of the mill "bad guy wants to destroy the world for reasons" actioner that we've seen done better many times before.
Don't get me wrong. The movie's fun. The dialogue is frequently clever and humourous. And I really appreciated the quiet bits of storytelling that Whedon was able to sneak in. It's just that at the end of the day, the villain is weak sauce, there's way too much set up for other movies, and if I'm criticizing Man of Steel for having excessive destruction, I can't give Avengers a pass since they needlessly blow up not one, not two, but three cities. Pretty sure many insurance agencies went bankrupt paying out all the victims.