I think the problem was that, despite Joss Whedon's claims that he wasn't doing a rehash of the first one, it still ended up being a rehash of it. Any scene that wasn't on Barton's farm or setting up a future movie was just a soulless copy of the first one.
Hell, I'm pretty sure for the climax they just copied and pasted the final battle from the first movie but replaced Chitauri with robots and Wormhole with flying city. It's kind of like the Hangover 2 of the series.
"How come nobody's ever tried to be a superhero?" - Dave Lizewski, 2010.
I feel like Age of Ultron couldn't have possibly been more different from the first film in my opinion. The Avengers don't form until the third act of the first film, whereas in Age of Ultron, the team is there thirty seconds into the movie. That sounds like a small difference but it completely changes the structure of the two films, plus we get new characters, Ultron's motivation is nothing like Loki's and they dig deeper into why the Avengers do what they do and provide Ultron with a great argument as to why that may not be what's best for the world.
This. People who get easily distracted by splosions tend to miss that these are character driven movies first. If you don't at least graps that much, you miss 80% of what's going on.
TA seemed just a set up movie. Most of the movie was them trying to come together, which they do at the end.
AOU starts with them as a family and interacting. While some have said they are trying to 'come together' in this one. I disagree. This is about them working through a problem as a family.
No, because my major gripe with Ghostbusters 2 was the jaw-droppingly stupid ending. Even in terms of the movie's own internal logic, "Hey, let's spray the inside of the Statue of Liberty with goop, which will let us pilot her like a jaeger!" was a huge WTF moment.