The more I look into Age of Ultron, I hope the basic plot is different. It feels so much like the first movie.
Ultron/Loki want to destroy/rule the earth. Avengers say "oh no you don't." Ultron/Loki has a plan to pit the Avengers against each other and split them apart.
Cue interhero fights: Thor vs. Iron Man. Thor vs. Hulk. Iron Man vs. Hulk.
Hawkeye gets cast under Loki's spell, goes against his former allies. Until he gets rescued and rejoins the team. Scarlet Witch and Quicksilver are under command of Ultron, go against future allies. Until they get rescued and join the Avengers.
Captain America and Iron Man argue and bicker back and forth. Until they realize they have to put their differences aside for the greater good.
Loki's master plan is to bring an endless horde of aliens. Ultron's master plan is to unleash an endless horde of robots.