I will say this: I can't believe I've watched 17 - SEVENTEEN - movies in less than a month, all related to the larger story-line. Every MCU film I watch makes me more disappointed in the Star Wars and DC universes, and how those franchises have underachieved.
They definitely set a high bar, but DC had no problem stumbling, falling down and simply crawling underneath that bar time after time.
And yet teh MCU... some I liked better (Dr. Strange; both Guardians) than others (The Incredible Hulk, Captain Marvel) but I have yet to watch one where I said "wow, that was a wasted two hours!".
The good thing is you took the plunge. I’ll never understand the reasoning of those who don’t.
I always meant to - although mostly DC and Fantastic Four, I'm a comic book fanboy from way back - but since I rarely see movies in the theater, it got to where I thought I would wait for a couple films to come out, then it quickly got to where I was WAY behind, it was out of hand so that it was almost daunting. Finally with COVID and my daughter being home from school we bit the bullet.
Ultron; I liked it a lot, actually. Generally I like the interactions between the heroes, and I like Tony Stark, so the more that he's interacting with the other Avengers, I'm having a good time. I'm a huge James Spader fan, so there's that, too; his voice was PERFECT for that character. I'm still not sure I understand the Thanos storyline; I may need to supplement that a little bit. I think the only criticism I can reasonably see for that movie is that it's the first time the number of characters gets a little unwieldly. That, and it's the most we've seen of Clint Barton, who, frankly, does absolutely nothing for me (my daughter and I go around the house doing that stupid "shake" move where he opens his bow; we're not being complimentary, and we jokingly count his arrows). Overall of the 17 I've seen, it's probably in the top half, but not in the top quarter if that makes sense.