First of all, it suffers from what TV Tropes would call the Eight Deadly Words: "I don't care what happens to these people". I won't fault the acting; I feel the actors did the best they could with the writing they had. It's just that I thought the writing was extremely uncompelling and there was nothing about the characters which made me want to learn more about them or their troubles.

Secondly, I don't like the structure of the film. It's a melodrama, a type of story that I do not enjoy by default, with some plot points that are so heavily telegraphed that it sucked the energy out of the film. The multiverse structure that the film relies on was uncompelling to me. The action scenes lacked any sort of visceral impact to bring them back down to Earth; they were so obsessed with flashiness that there was nothing for me to connect with.

And thirdly, while I can enjoy absurdist humour, this film felt like it thought it was cleverer than it was throughout. I've heard a description elsewhere of this film as "nicecore Rick & Morty" and while that's awfully reductive, it still gets to the root of some of the problems I had with the film.