The author kinda feels like /tg/ nerd at times, what with grounded worldbuilding and focus on monster anatomy and ecology. /tg/ actually has regular dumps of the manga, they seem to love it too.
The comedy is great. There is a shift to more serious storyline as the manga goes on. I'm not entirely sure about the nature of the main antagonist and how he fits in with the themes of the story, but honestly, the drama is as good as comedy in my opinion.
The characters are likable, the art is clear and distinct, everybody has their own consistent worldview.
A genuine gem of a manga. I honestly can't think of any major flaws it has. Some people probably won't connect to its leisurely tone, maybe, and I guess the setting is kinda generic, though what's there is written really well. I'm grasping at straws here.
It's just pure quality, in my opinion.