Can't really compare it to "The Last Kingdom", which is more an historical drama.
This has more magic and monsters than even "Game Of Thrones". In the world of "The Witcher", pretty much everyone knows and accepts monsters and magic exist.
A Witcher is basically a hit man people hire to hunt monsters. They are taken as children and mutated with magic and potions to make them super human. They can use magic, potions, etc. to give them an advantage in combat.
That's just Geralt's story though. There is two other characters (Ciri and Yennefer) that are very important later on, so the show focuses on them a lot too. There's a bard character (Jaskier, aka Dandelion) that is straight jokes.
The only major complaints are:
1. The CGI is ass in some scenes, probably because Netflix didn't know exactly how much money a series like this would cost. But the first season was a hit so I expect a budget increase for the 2nd season.
2. This didn't bother me but there is three separate time lines going on, that follow Geralt, Ciri and Yennefer. If you aren't paying close attention there's no indication other than dialogue (and previously dead characters being alive) that they're jumping around. Also Geralt, Yennefer, and all the magic users in the show don't age....so they took the same even though 30 years have passed.
Anyway, it's a dope show. You should check it out.
Fred.