Story isn't everything.
This movie didn't have any major flaws, they were only little tidbits that could be found in any other anime regardless of how popular they were.
The reason KnY stands out to me than other shounen is because the series doesn't feel stretched out unlike other popular shounen. The story actually flows and progresses each arc we get closer and closer to our end goal. The MC is actually really cool he may be pure and sympathetic, but he can get the job done without any sort of hesitation. Inosuke is pretty good, Zenitsu can be cool from time to time. Nezuko is a
really great little sister, she isn't like your typical little sister in anime. Everyone else has their own quirk. So really the animation and music used in this anime only acts as a bonus that puts the show at a greater level.
So overall this movie was really great and highly recommendable.