I just got back from an IMAX 3D screening.
There was no Force Awakens trailer, which was very disappointing. Instead there was an extended preview / scene from Tomorrowland (which looks great) and a trailer for Jurassic World (which does not). Would really be interested in hearing whether people get TFA trailer when they see Avengers.
As for the film:
What an amazing opening scene. It instantly brought me back into the fantasy of the first Avengers and was a great way to kick off the sequel. I also really appreciated how well the TV show SHIELD led into AOU. I thought the party scene at Avengers tower was also light-hearted and fun.
And then, piece by piece, the film fell apart to me. It got muddled, lost focus and lost its pacing. Most importantly, I think it stopped being fun. That's not to say there wasn't amazing action - because there was - it's just that it started to become meaningless and (as ridiculous as this will sound) unbelievable.
I didn't buy into Ultron's plan with the...
...and thought Spader's portrayal was over the top bordering on silly, and not scary or menacing enough. For hell's sake he was "begging" for the twins to stay his friend.
I also thought that they tried to shoehorn way too many Marvel components into the story, and for the first time in a Marvel movie, the film suffered for it. Too many plot threads with none receiving the proper attention.
I know people are praising the attention that Hawkeye got in AOU but I'm not sure why that's a good thing. The sequences with his family are cliche ("come back to me in one piece hunny") flat out not interesting and take up way too much screen time. Backstory wise, he's the least interesting of the Avengers by a long shot and this film convinced me that I want to spend "less" time with Barton.
Whedon could have devoted that time to any number of more relevant threads like further fleshing out Black Widow's past, diving deeper into Banner's desire to "hide," the resurrection of SHIELD, von Strucker (who was utterly wasted) or the deeper cosmic implications of another infinity gem being handled.
I also felt Whedon betrayed a lot of the "rules" of the universe, some of which he created in Avengers. Captain America took an awful beating from Ultron (getting lasers shot at him at what not) and didn't suffer a scratch. He was doing some pretty impossible things yet in Winter Soldier and Avengers he actually hurts when he's blasted by aliens and tasered by Hydra agents.
I know these are super heroes and this is Marvel, but I never bought that the Avengers were being seriously threatened.
Killing off Quicksilver (wtf?)
...seemed like an acknowledgement that "yeah, we gotta do SOMETHING here or else nobody is ever going to buy that these super heroes could possibly lose."
The mid-credits scene was cool for what it represents, but it didn't feel earned. It was also the shortest and least excitable of the sequences.
I'm still digesting it, and will probably see it again to soak it all in, yet I'd give it a 7/10.