Just rewatched it and the worst thing about this movie is the action. And it mainly being an action movie that is a big problem. Ultron has 0 interesting or cool fight scenes. He flies around and shoots people with blasts but he never does any serious damage. And the entire mass nameless droid soldiers thing is tired as hell. We got it with the alien race in the first Avengers and the last Thor. That shyt needs to be retired.
Seeing it the second time Ultron's creation and purpose after the fact make more sense. He was created directly after Stark's mind is fukked with by Scarlett Witch and he had just seen and felt his worst fears realized. He was operating out of fear that's why Ultron is all taking shyt to the tenth exponent. That's the difference between Jarvis and Ultron I guess, Jarvis was created under normal conditions.
And the best thing about this movie is seriously the dialogue. Yo, getting super heroes/unbelievable characters to have lengthy and meaningful conversations with one another and it seem somewhat believable is an extremely hard trick. This movie does it well. Stark and Cap's argument chopping wood, Ultron shytting on Cap, Ultron explaining the meteor master plan to Black Widow, Hawkeye explaining the current situation to Scarlett Witch, Stark and Fury in the barn. Vision and the rest of the Avengers after he is just created is all good stuff.
Also, the foreshadowing for Civil War, Thor 3 and Infinity War is dope as well. They advanced the entire MCU plot well. I guess they sacrificed the story here and now to do so though.