This one is much shorter than the previous ones, but it's made up almost entirely of completely new footage.
Spoiler-free impressions: It's an enjoyable movie that takes its time to build up. It's certainly a much better experience to watch after seeing the other Marvel movies first, otherwise you'd be confused at all these minor characters and why they'd matter. It's full of the laughs you'd expect from a Marvel movie, and explores the characters at their lowest point after suffering an unimaginable loss. In particular the focus is on Thor, Captain America and Iron Man, whose performances shine brightest, while everyone else other than Black Widow, Nebula and Hawkeye kinda fade into the background. For those worrying about Brie Larson and Captain Marvel somehow ruining this movie, you can put your fears to rest. She's used sparingly and appropriately.
I'd give the movie an 9/10. It ain't the next Citizen Kane or anything; then again, I never really enjoyed Citizen Kane all that much. Not my cuppa. Anywaaaay… it's a great popcorn movie, full of thrills, spills and bittersweet moments. I didn't give it a 10/10 because I feel it stumbled in a few places, namely in the method in which they try to undo what Thanos has done, uneven character development, and less patient viewers might feel blueballed in the first act.
Okay, spoilers below, customary warning not to peek until you've seen the movie, yadda yadda yadda.
Thanos: Retired, then killed by Thor when he goes for the head. Then his past self goes forward in time to take the Stones the Avengers so helpfully collected for him, and gets killed by Tony using the Infinity Gauntlet.
Tony Stark (Iron Man): Deceased. Dies by using the Infinity Gauntlet to kill Thanos and his army. Fans are going to miss him.
Thor: The Big Lebowski. Ok, that was a bit mean-spirited. After his loss to Thanos, he goes on a downward, drunken spiral. After going back in time to talk with his mother, he regains his confidence, helps the Avengers finally end Thanos, and cedes the throne of New Asgard to Valkyrie, feeling that he is no longer suited for the role. He joins the Guardians of the Galaxy, where hilarity is sure to follow.
Rocket Raccoon: A much happier rodent since the Guardians' deaths were undone.
Nebula: Her past self is dead after her present self shoots her past self who attempts to sabotage the Avengers' plan. Which means she's dead, but she's not, since she's still with the Guardians at the end, but her past self is dead, meaning that she never betrays Thanos to join the Guardians, and oh my god, I really hate time travel.
Hawkeye (Clint Barton): Grieving. After losing his family to Thanos, he becomes a cold-blooded vigilante, and attempts to sacrifice himself so Black Widow can get the Soul Stone. It doesn't work out that way because...
Black Widow (Natasha Romanoff): Deceased. Dies after sacrificing herself so that Hawkeye can retrieve the Soul Stone. Bruce tries, but fails to bring her back with the Infinity Gauntlet. Guess we're never getting that Black Widow movie she deserved.
Hulk (Bruce Banner): Has a burned, mangled arm after using the Infinity Gauntlet to bring back everyone Thanos wiped out. Has now achieved balance with the Hulk, though I wish there was a proper scene where this is shown in the movie, and not handwaved by a timeskip.
Scott Lang (Antman): Was stuck in quantum limbo during the fingersnap to end all fingersnaps, but eventually returns, and uses the knowledge he's learned to create a time machine to collect the Infinity Stones before Thanos can. He attends Stark's funeral.
James Rhodes (War Machine): To be honest, I don't remember alot of what he does. He's definitely still alive at the end, though like most of the other characters, his limelight is outshone by Captain America, Thor and Iron Man.
Steve Rogers (Captain America): Retired. During the climax, he wields Mjolnir (retrieved from the past) against Thanos, prompting Thor to shout "I KNEW IT!" He's sent back in time to return the Infinity Stones, but chooses not to immediately return. Instead, after returning the Stones, he lives a full life with his old flame Peggy, and as an old man, hands his shield to Sam Wilson (Falcon).
Anyway, I'm mostly in agreement with your overall assessment of the movie. It was a very satisfying and fulfilling culmination of everything that had come before it, and would, in fact, work as a definitive conclusion to the entire Marvel Cinematic Universe...if it were going to end, that is.
In fact, it's such a satisfying conclusion that, in a strange way, part of me almost wishes it was.
In addendum, there are a couple of specific things I want to highlight.
- It's really difficult to imagine how the final battle at the end of this movie could possibly have been any more epic than it was.
- Up until now, nearly every movie in the MCU, with the exceptions of the first Captain America, Guardians of the Galaxy vol.2, and Captain Marvel, have been set in the "present", or more specifically, in the year in which each movie was released. That's going to change now, however, with the MCU having collectively jumped ahead to 2023 thanks to the five-year time skip in Endgame. It's also worth underscoring the fact that although its direct effects have been undone, Thanos's "Infinity Snap" will have heavy and permanent consequences, because the universe and all its survivors continued on through those five years, bereft, while those lost were consigned to oblivion. Scott Lang's daughter Cassie literally grew up without her father during that time, and that's only one of what will surely be countless examples.
- Regarding that Black Widow movie, apparently that is still happening, but it's going to be a prequel or something. Not sure how I feel about that, at this point...
- While this was most obviously true for Tony Stark and Steve Rogers, I think that all of the original Avengers were able to finally reconcile with, or otherwise address, their greatest regret. Tony with his father; Steve with Peggy; Bruce Banner with the Hulk; Thor with his mother, and through her, with his father's expectations; and Natasha Romanoff with her desire to atone for her past. The only one who that arguably wasn't true of was Clint Barton, AKA Hawkeye/Ronin.
- I guess Thor is joining the Guardians, now? That should be...interesting. And unsurprisingly, it looks like Star-Lord is going to want to track down Gamora. But the problem with that idea is that the Gamora who's alive now is from 2014, nine years in the past. She never met him, never became a Guardian, and certainly never fell in love with him. So while she may be back, her entire character arc from the previous movies has been lost.
- Exit question: How awkward do you think it was when Captain America went to give the Soul Stone back to the Red Skull?