I liked it a lot. It's set in a standard fantasy world, with elves, halflings, demon kings, adventurers, etc. Technically, it also has an isekai hero who ends up being far stronger than everyone else around him. (Negligible attention is paid to the isekai thing and it makes no difference to anything, but it's still there.)
Importantly, though, the show's taking itself seriously and throughout is both intelligent and sincere.
Our hero is a baby called Will. (He'll grow up, obviously, but we follow his life from pretty much the beginning.) He has three undead parents: a grumpy ghost wizard called Gus, a mummy called Mary and a big, shaggy-haired skeleton called Blood. Are they his biological parents? When did they die? Never mind. Those questions have answers, but you'll have to wait for them. For the time being, they're just bringing up a human child in the otherwise deserted City of the Dead, teaching him all their adventuring knowledge and trying to ensure that he'll be a good boy.
That's a lot of adventuring knowledge, by the way. When they were alive, they were legendary. Blood and Gus both make Will formidable in their specific fields, although this takes many years and absolutely has to be earned. (Gus is curmudgeonly, while Blood is a good friend but a scary teacher.) As for Mary, she makes Will polite, modest and religious. (Very, very religious. In this world, you would be too. This is fantasy, after all, where gods might appear and reply to your questions, while a cleric can perform miracles on demand by praying. It's interesting to see devout faith taken so seriously in the characterisation, while also being part of the plot and worldbuilding.)
The show's not about monster-bashing. Admittedly, there will be plenty of that too. Demons are a threat to the survival of human civilisation and have driven us out of the south territories, but the show's aware of less simplistic problems too. There's politics, with city governors and fat bastard temple priests. (When Will asks a king for permission to raise an army to wipe out demons, this might sound like a good thing but the ruler still considers killing Will.) Will's friends will include a merchant and a halfling bard, both of whom are useless in a fight but invaluable. Villages starve, have disputes and need arbitration. Saving people isn't as simple as killing monsters, if the entire region has a shattered economy.
It's a strait-laced series, but not without moments of comedy. Will's upbringing leaves him amusingly in awe of the first city he visits, for instance. It's a wonder to him that there can be enough people to have a concept of fashion. Mind you, he's also capable of misjudging himself and making some punch-in-the-face bad decisions in ep.12.
It's a strong, intelligent show. It has some cheap art and shoddy animation, mind you, but I don't care about that. The second season's very good too.