The other reviews have already explained enough about the artistic part of the show, I would just like to talk about the underlying story. After watching it twice, I understood the following: the girl is an art student who is producing fake copies of artworks to make (lots of) money, and when she meets the boy she is close to being caught. The boy is an artist too and at the beginning of the film he seems to be holding a draft of a children's book. He is making a children's book, and I think he wants to pursue a career in children's literature. At one momentshe is chased by cops, at another she is chased by detectives, at another she seems to be chased by goons (the night scene where the boy knocks one of them down, the couple runs and the girl loses her shoe) who, I assume, were sent by the boss who ordered the artwork for her (she may have betrayed him).

The abstract scenes are showing what they are imagining as they talk, so the themes of the conversation guide what appears in these scenes. For example, there is an abstract scene in which they seem to be discussing the girl's self-esteem, one with televisions and little robots.

Near the end of the film she is arrested, and the boy doesn't know what happened or where she went (it seems he doesn't know she was involved in crime, she must have cleverly hidden it from him).
But he keeps passing by the places where they used to meet, and some time later (some months I guess) she is released and they meet again. At the end of the film it is also hinted that he managed to publish his first book.

I like musical movies in general, and I found this movie interesting to watch. Unfortunately the film art has its ups and downs when it comes to quality. I didn't like the music very much, but it suits the scenes. And I found the abstract scenes very creative, for me they are the film's strong point. Given the film's problems I consider it good, but it certainly could have been executed better.
I would also like to find more films that make a surrealistic and experimental exploration like the abstract scenes in this one.