Massive waste of time. Could've been an hour and a half to tell a better story. It's like the directors gave up editing/removing parts that don't matter.
Edit: can't explain why without major spoilers, so if you don't want any then don't keep reading.
The movie starts with the avengers rebanding together and Thor kills a helpless Thanos. This was fairly pointless. He didn't have the stones so they decided to go back in time. This means banding together, a process that reintroduces characters halfway like "oh hey, remember this guy?" Thor got fat, hulk is basically x-men's beast (merged intelligence with a mild dose of hulks strength as you see later) at this point, and not much else stood out. The story drags out needlessly in an awkward attempt to pad out whatever contractually obligated screen time they gave to each actor. The time heist was okay with a minor mess up that Tony solves like it's nothing. No real suspense, just a quick solution. Most explanations on how they got the stones were irrelevant copouts.
They get all the stones in the past and Thanos follows them to the future through one of his lackeys opening a portal just as hulk snaps to get half of all life back. Iron man, Thor, and Cap fight Thanos for a while and the only standout thing worth noting happens in this fight while they interject yet even more pointless story and reused jokes from previous movies. Thanos summons his army and the avengers assemble in full force. Of course they win with one casualty (someone sacrificed themselves) the next... Hour is them wrapping up the story for what I assume is actors whose contracts ended.
Most of this was a boring waste of time. I could've done without Tony's 'comical nicknames' for characters or the other rehashed jokes. I could've lived without the poorly written back story on what happened after killing Thanos and how they formed the avengers for the umpteenth time. Overall, I could've just waited for this on streaming.