Vol 1: ★★★★✫
It was a great start, the art was beautiful. The real world allegories were obvious and well done.
Vol 2: ★★★★
Still very good, but a little less gripping. The mystery also started becoming strange.
Vol 3: ★★★
Everything was resolved very quickly and strangely, so I didn't like it as much as the first two, but it was still good.