I recently finished watching this anime, and I liked it alot. The artwork was gorgeous (gotta love the way they draw the eyes!) and well-detailed, and the mood was melancholy and fairly dark, which I highly appreciate. To me, the music felt kind of average, nothing that I'd go around humming although the intro grew on me for every time I heard it. But overall, I liked the show very much. The one thing that could need improvement would be the lack of character developement.
Spoiler for the last episode:
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For those of you who have watched the whole show, what are your theories about the ending? Did they reach Paradise, at which the world was reborn? Or was Paradise and Earth the same thing all along? Me, such an open ending surprised me, but in a good way - I love those kind of endings.