I'mma come out and say it: It's a godsdamned mess, and I loathe it even more than Infinity War - and believe me, I've got bones to pick with IW.
But to stick with Endgame, for one, Erynn Brook was onto something when she pointed out the whole Girl Power Moment with Captain Marvel feels distinctly hollow when taken in the context of a film that wastes multiple women, but can make time for Tony to have a masturbatory chat with his dad, a background facet we already had closure for back in IM2. This is a film that drops Natasha off a cliff, rolls Gamora back to square one, has no idea (cannot have any idea, because it was filmed first) what to do with Carol, and has Okoye apparently in charge of Wakanda in flagrant disregard for any notion of Wakanda having its own way of doing things... but it wants props for having a big Girl Power moment that has no impact going forwards. Only Wanda really feels like she gets some decent respect, so at least the Russo's can remember that they had her holding off a fully powered Thanos in Infinity War literally one-handed, but the vast majority of the ladies deserve better.
Cap's ending isn't great either. The film wants me to believe that Steve Rogers totally dismissed the family he'd found in the 21st century, abandoned Bucky, and hared off back to the 'ideal happy ending' of... A conventional white picket fence nuclear family in the 50's? STEVE ROGERS?
Look, I'm very sympathetic to Chris Evans' desire to put down the role so he can stop having to maintain the frankly absurd physique it requires (dude probably like, scarfed down an entire loaf of bread with tears in his eyes once shooting wrapped up, the poor sod), and I can see Steve wanting a break in-universe as well, after all he's done. But Steve "I can do this all day" Rogers, drifting quietly through the 20th century without making waves? That's a crock of s***.
It's... interesting who the Infinity War narrative is cruellest to; both Nat and Thor are people who either can't or won't buy into the reactionary obsession with the nuclear family. And holy s***, poor Thor! After Ragnarok gave him an actually pretty neat arc and some of the most character growth since his first movie, Infinity War walked it all back, from "Asgard is a people, not a place, you are not the God of Hammers, and this wisdom you have paid for with the price of one of your eyes, as Odin did before you," to "welp, let's kill most of the Asgardians, give Thor a new hammer, and oh yeah, let's make a poop gag out of giving him another eye, too," and now Endgame doubles down on that by using the character as punching bag for frat boy abuse about PTSD victims being pathetic and fat and useless. Look at him scream at this child on Fortnite, what a loser! See him refuse to save the world until he's promised beer, then drink in every scene. Look at him try to step up and bear the dangerous power of the Infinity Stones with the strength of what flows through his veins, only for Rhodes to dismiss that as cheese-whiz. Look at him break down in an actually pretty great and earnest portrayal of PTSD by Chris Hemsworth, only for Rocket to slap and insult him, because everyone's lost things, you're not special so your pain isn't worth sympathy. "Look at the fat, drunk loser," says the film's framing, "laugh at him, he’s pathetic and he deserves it."
(Minor note: I cannot IMAGINE how outraged Tessa Thompson must be right now, after trying so hard to put an explicitly bisexual Valkyrie on the big screen and having it shut down, that on top of walking back basically all of Ragnarok's character work for the sake of gross fat jokes at the expense of a dude with PTSD, the Russo's also got to claim credit for inserting themselves into the narrative as the first on screen LGBT character in the MCU, as a godsdamned bit character.)
There's some great acting in this film. Scarlett Johansson's performance with Jeremy Renner is heart-wrenching. Chris Hemsworth's does frankly phenomenal work of making what he's given (and oh boy what is he given...) shine. Gwyneth Paltrow makes full use of her brief time in the limelight to actually grab some character development while she can. The acclaim these actors have accrued is fully earned.
But no amount of good work by the actors can paper over how much of a howling trainwreck the script is.