More than I expected, would be how I would summarize this series in brief. I came to Species Domain looking for cute fantasy girls doing cute things and I was not disappointed, since there are a lot of really cute expressions and some genuinely funny moments. However I was surprised that this manga did seem to go the extra mile whenever the chance, be that through plot twists, attention to detail to secondary characters or just a heartfelt, honest examination of it's characters. For a non-spoiler example elve/dwarf/other fantasy people are not just born in the world of Species Domain, but swapped with other human babies. Thisis a nod to the changeling stories and fairy tales in our world, but aside from that I felt it was somewhat needlessly complicated, since the premise of fantasy people born into a otherwise realistic world did not require it.
However the manga uses that premise to actually explore the feelings of both the main cast and their families, acknowledging the complicated feelings that come with the main characters all being basically adopted.

At the end of the day, it's a fun read and not a heavy drama, but it's not shallow by any means and also manages to be entertaining on a baseline level throughout.