Story
The series has a calm and kind atmosphere about it. Even in dangerous situations it feels mostly calm somehow. Also I find that it flows well and mostly isn't predictable which makes it very interesting to watch.
Art
Beautiful art style. Fits well with the story.
Sound
The music and sound/s are awesome. The character voices fit well.
The opening and ending are beautiful and fit the series very well.
Character
The characters are lovely. Maybe it's unrealistic that they're all so kind and reasonable (and if they're shown unkind and later turn out kind in their core) but I love them.
Enjoyment
I love it.
Overall
There are few situations that seem unrealistic but overall it's an awesome series/season!