When talking about fantasy books being made into series or movies I am usually at the forefront, having read most of what is now being considered for the screen. Witcher is different for me since I have not yet read anything written by Andrzej Sapowski or even played the games.
Witcher is a series of books written first as a set of short stories and then full length novels. What I gather from what I have seen and read about the series (written and tv) the feeling is like the old Forgotten Realms books BUT they keep central characters, like Geralt, Yennefer, Ciri etc.
I will be delving into the reading, however, right now I am truly enjoying entering a fantastic realm first through TV, then the writing.