This Movie Was Awesome
I finally got to see this, and frankly, I don't see what all the criticism was about. I don't see what more anyone could expect or want from such a movie. Yes, you had to pay attention, but that's not much of a criticism. I think the main difference between the first two flicks is the first one was aimed more toward the casual fan, while this one was more for comic book fans.
The idea that Ultron was not a threat is ridiculous. He nearly pulled off an extinction level event! If that's not a threat, I don't know what it.
You got to see the introduction of Quicksilver, The Scarlet Witch, and the Vision. And while there was no one great scene like Hulk trashing Loki, there were a lot of cool moments like the Hulkbuster armor's "jackhammer" fist.
In fact, I was surprised how nostalgic it was to see Quicksilver and Scarlet Witch on screen. But those characters are nearly as old as Thor, the Hulk, and Iron Man. I dislike that they killed Quicksilver off though, those two characters belong together.