I'll be very careful not to spoil anything, because with this type of movie, pretty much anything you say might be a spoiler. Loved it. It's incredibly character-driven and the interactions of the impressive cast are cleverly scripted and performed. There's an emotional intelligence to at all that is quite admirable. The visuals are astounding and it makes me very happy to say that. I've been watching MCU movies for quite a while now and I liked a good amount of them - at worst I found them entertaining for an hour and a half if spotty, at best really good to great. But more often than not, the thing I liked least about them was the visual style - too sterile, too uninspired. Lots of clean, modernist interiors, grey skies and flat lighting. Someone once compared Civil War to looking at an empty parking lot. I'd have to agree with that, even though I really liked it for its writing, plot and characters.
Recently however, they started to be a bit more vivid. And Endgame has finally reached a point I'd consider to be fully cinematic - good framing, inspired camera work, well utilized color correction, beautiful strong contrasts, fine depth of field and some gorgeous locations - both real and computer generated.
And the score, fuck, the score. Bar Black Panther, the Iron Man theme, the main Avengers theme and maybe some parts of Winter Soldier, I struggle to remember any memorable piece of composed film music in the earlier movies. They were all just kind of there, meandering away in the background. Endgame however has a very lovely, very emotive score. And choice of songs for that matter. I'd have a lot more to say about plot elements and other aspects, but I'm afraid that would venture too much into spoiler territory. In a nutshell: Probably one of the best MCU movies, certainly the most cinematic.