Infinity War is a pre-season finale for an incredibly well-established season. You take it as an action packed movie that lacks character development as a standalone (wrong), or you take it as the culmination of the 18 prior films (right). It's not meant to stand on its own.
I remember reviews from when IW came out and there were a couple of reviews that said there was no characterization in the movie, and that was everyone's rebuttal. It's the correct response also.
Like, there's ten years of characterization. You don't need one movie to rehash all the characters for you.
I know some people feel like you shouldn't have to watch so many movies to be able to follow one movie, but this is like the one time that's the case where there isn't a number in the title.
I get that argument, but it doesn't save the movie from being lame.
Let me put it a different way: the only character that needed to be established or developed was Thanos, and they botched it. His motivation is terrible; a misguided desire to save others from overpopulation by wiping out half of all life in the universe? TERRIBLE, and seemingly out of character from what we've seen in other movies. The rest of the three (plus) hour movie could be a superhero montage shot if they do an appropriate job handling the villain... failing there make the whole thing cheap and meaningless filler.
If it was 90 minutes of cheap filler, featuring your favorite character, awesome.
If it were 2 hours of cheap filler then it's probably overstaying it's welcome... but I'm sure fans will be happy.
Over 3 hours? F*** that; waste of my time!
I strongly believe the reason this full series of Marvel films was successful is because of the characterization they've provided. The films that do a good job handling the characters tend to be the most popular while those which are weaker tend to be less interesting or popular.
To give the Avengers movies a carte blanche simply because other movies came out first just isn't how I roll. That said, maybe the pay-off is all in Endgame and I have to view it as a 6-hour epic... With that kind of run-time it will need a
pretty significant pay-off, but maybe that comes to be. I'm not holding my breath though.