I think the movie could have used another 10-20 minutes to flesh some things out (Carol vs the Supreme intelligence, Monica finding out that Carol did actually visit her mother and the fate of the singing planet) but I honestly had more fun with this than with most post-Endgame MCU movies (maybe with the exception of Shang-Chi and No Way Home) so it's an A from me.
My go-to example of a movie that is so fast-paced that it becomes nonsense is The Rise of Skywalker. I remember walking out of the theater and thinking "this is not a movie". The Marvels is not that.
I think it could have used a few more scenes here and there to flesh things out but I didn't think it was disjointed either. It's definitely not a cut up mess like some have suggested (I saw one critic comparing this to Josstice League which is just absurd).
So if we discount the Ms. Marvel post-credits scene (filmed for The Marvels) and the aforementioned Quantumania post-credits scene (scene from Loki S2) then the only post-Endgame post-credits scenes that have been paid off are from the end Black Widow (sets up Yelena vs Clint in Hawkeye) and both of the WandaVision scenes (Monica gets recruited by Nick Fury and Wanda messing with the Darkhold).
I'm actually one of those people who ended up really liking the movie so I'm hesitant to claim that the people who praised the movie were full of shit.
If you've been following social media reactions for even a short time then it was pretty obvious that they were not glowing. Understanding how they translate to reviews requires reading between the lines a bit.
And now they're probably also worried about promoting any characters originating in a Disney+ show. If we're just considering movie characters then we have Hawkeye, Thor, Hulk, Doctor Strange, Spider-Man, Captain Marvel, Shuri, Yelena and FalconCap (and movies starring the last two might bomb before the next Avengers)..
Just got back from seeing it and I honestly loved it. It really doesn't deserve to get lumped in with Quantumania or Love & Thunder. I'm legitimately sad that critics are trashing it and that it's going to bomb miserably.