Hatsune Miku is an icon sadly this movie is not too friendly for people who are not familiar with the video game it comes from.
I say this because there are around 4 or 5 different groups each of them has around 5 artists in them, the movie jumps back and forth between them constantly and it doesn't explain very well who they're, what they do... (You can guess though) Why each of them has a variant of Miku and other Vocaloids.
Later on after investigating a bit i understood that these are recurring characters of a popular video game, so if you're not familiar with this then you'll be confused with these groups
Because of this i think the story wasn't very good, it felt like a bunch of things where happening just for the sake of it.
The animation itself is really good specially in the dancing & singing sequences.
Soundtrack is good but they left the catchy songs towards the end.
There's one thing to dislike in the Spanish subtitles: At least for the North America release the majority of subtitles are hard to read on colorful scenes because the text blends with it.
I thought just coming up to this movie just knowing "Hatsune Miku sings and it's popular" was enough to enjoy it but it was an overall confusing experience for me.