I am biased here because this is my favorite anime and manga work
-amazing soundtrack by hirasawa susumu (forces, sign, earth etc)
- very dark and shocking
-very mature, deeply human and religious themes
-good love story
-Overall i think this story (the golden age ark) is a beautiful representation of how hard you have to fight and grind to get through life and how short your prime, hapiness, moment in the sun is before you age and existence turns ugly and you can only remember the good times.