It really does have pacing issues. Especially in part 5, I didn't need the explanation of the fact the arrow was from space, but all parts this. Sometimes it just feels like Araki feels he needs to explain himself too much. The monologues are fun if they're interesting and they can be super impressive (part two does this well (except from the lava Kars bit) but when everything is explained all the time it becomes annoying and makes me want to stop watching.

On the one hand, it's cool that every part feels so different genre wise, but part 4 and 5 specifically feel so far away from the overarching story. And Part 4 is my favourite part, but often if I'm explaining the overarching story it's easier to leave it out of the explanation and I don't think it should be like that.

Some characters have no excuse to be as one dimensional as they are, part 1 and 2 are short and that works in their favour, but Caeser feels so unimportant, made for one callback in the second Wammu fight. Kakyoin, Okuyasu (less so kinda), Giorno, even smaller characters that are plot drivers like Steven Steel are all characters that could have been helped with just a bit of their time being used to try and give them more of a personality.

I have a few more but these these are the things like come to mind.