These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Crowning Music of Awesome: The soundtrack is beautiful. Even the short, simple main theme is profoundly emotional to listen to.
The full version of the main theme can be Crowning Music of Funny once you hear it. The TV size version lyrics go really well with the mood of the show and personality of the main character. The second verse though...not so much
"I stole ten-thousand pounds, ten thousand pounds to see you.
I robbed convenience stores because I thought they'd make it easier.
Fridge Brilliance: Ginko's remarks in episode 20 about being unsure how much longer he'll survive seem reasonable enough given his line of work, but take on a whole new level of meaning when you remember that he is most likely fated to turn into a Tokoyami one day like Nui.
Paranoia Fuel: So much. Two examples being episode 4 (Had a nightmare recently? It may become reality) and episode 17 (Don't. Ever. Close. Any. Door. Or be in any completely closed place. Not even for a second.)
Squick: Via Body Horror in season 2, episode 9. A mushi causes a breastfeeding woman to bleed and cry milk.
Stoic Woobie: Ginko, aware that his days are numbered and forced to walk the earth because his presence will inevitable bring trouble to any place he stays too long. He mostly seems to have made some degree of peace with his situation and never really complains, but his reactions to other characters who have strong ties to a single place where they've settled makes it clear that he envies them, and in "Those Who Chase The Rainbow" he joins Kourou in his search as a "vacation" from his constant otherwise-aimless wandering.