Personally, I think the movie was great. The animation was amazing, the characters were well written and had great chemistry with one another. The film also had great pacing as it had beautifully animated action sequences placed between long dialogue-heavy scenes. The movie never took itself too seriously but knew exactly when to shift to a more serious tone. The excellent writing and animation was accompanied by a very well fitting and expertly composed soundtrack.
My only gripe with the movie is that it's ending was very poorly written. I did not like the cliffhanger at the end of the movie. The characters seemed to be preparing for the final battle and then the movie ended. They should've just shown miles realising that he's not in his own dimension and left it at that. This way we would not really have known what to expect and we would have no idea what all of the other spidermen were doing which would add to the mystery. The ending was more frustrating than enticing or mysterious.