I agree with the 63% AniList rating and the 5.5 IMBD ratings
I watched this because for a while it seemed like a lot of people who liked anime had really liked this movie. With that in mind, the best things about this movie were it's graphics, especially that underwater seen at the end with the fireworks going off above the water. Everything else either sucked or was kinda mediocre (pretty cliche, actually). None of the characters were interesting and in some scenes you felt like reaching into the screen slapping some of them in the face for being obnoxious, hypocritical or dumb.
Yeah, some guys might say that was the point, but other than the cool graphics there was no attempt to make the show, let alone the characters, endearing other than the guy gets the girl in the end - sort of.