https://www.cnet.com/news/avengers-endgame-review-three-hour-marvel-thriller-tops-infinity-war/

The shift in focus brings a shift in tone marked by the camaraderie between Captain America (Chris Evans), Iron Man (Robert Downey Jr.), Black Widow (Scarlett Johannson) and the rest of the heroes who headlined 2012's The Avengers. The villain-focused Infinity War was dark and deadly. This one goes lighter as it turns toward the heroes, with plenty of humor, and even some absurdity, mixed in with the heartbreak and insane action sequences.  

Endgame is a giant sequel to every MCU movie ever, but thankfully an in-depth knowledge of those films is unnecessary. The plot does jump around at times, which might confuse casual viewers, but bottom line: this thrill ride kicks off big and never lets up. It's so much fun.