This review may contain spoilers.
When I was watching this, the first word which came to my mind was "art".
The story can seem a bit poor, or maybe non-existent. But when it comes to true art, a story isn't needed anymore.
The minimalist music can seem bad, but it's not the case. This is pure art, so you probably wouldn't understand how beautiful is the music.
You may think that there isn't any characters, but you would make a mistake too. There are a lot of characters, symbolized by all the shapes drawn. Once again, this is holly art.
The drawing style seems a
bit weird? Don't worry, this is a work of art, and you are probably not enough smart to understand.
Simply put, the real problem of this anime is that I'm as stupid as you and I probably didn't understand how beautiful it was.