TL;DR: It's Marvel's total ripoff of Into the Spiderverse and is chock full of really awkwardly paced acting while the entire movie teeters on a really weak premise. Marvel cares more about cheap fanservice than good writing.

Do I really need to explain how this is a total ripoff of Into the Spiderverse? They literally just took the same concept and ran with it. Into the Spiderverse knew how to develop their characters and make you care about them, it had heart and soul. No Way Home lacks this.

So much of the acting comes off as extremely awkward. No one seems to be themself. It feels as if everyone was acting in separate locations and not even on set together. Also much of the lighting is extremely weird too. There's a lot of shots that are straight up distracting with how obviously green screened it is. In previous Marvel films, it hasn't been too distracting, but it's pretty darn bad here.

I'm pretty sure the directors had to meet a quota of at least one three-point-pose per fifteen minutes during this film, because Tom Holland has to strike that cliche superhero pose a dozen times throughout the film. Sure you could call it a nitpick, but it gets pretty tedious after the fifth time.

The entire premise of the movie is really weak. I wont spoil anything, but even Dr. Strange has a line that through the fourth wall questions the entire premise of the movie. It's really contrived, and ends up being a universe-threatening situation which just makes it feel too big for a couple of teenagers to figure out. (In other words, in universe, it doesn't make sense why no other Avengers or characters in the franchise don't get involved, thus breaking suspension of disbelief).

There's also a ton of half-baked code switching from several main characters. I get that they were trying to do the subversion of "Character wants the thing, but when they're about to get the thing they get cold feet and don't want it anymore." But the writing is so poor it just comes off as "I changed my mind because the script told me so," rather than actually making you believe the character had a change of heart.

In typical Marvel fashion, it's just an excuse to get a bunch of fan-favorite characters to hang out with each other, and literally wave a magic wand at the end to make the problems all reset themselves.