I have read the Witcher books and played the Witcher video games. I have lost friends because of how much I talk about Witcher ; ) ha ha ha. I thought I was going to hate the Netflix series but I actually really love it. The casting is great (with a few exceptions that have grown on me), the acting is great and the world is beautiful. I agree with the story lines they chose to follow and the quests they highlighted. I give the Witcher series a 4/5 because I can imagine it might be confusing for people who have not read the books because it jumps across different time periods. Something to keep in mind if your not familiar with Witcher series: the scenes with ciri are taking place in the present, while the scenes with most everyone else is in the past. The show is trying to show you how all these people come together in one moment in time, which is difficult to do with a series that has so much back story.
Anyways I recommend giving it a try and if you like it PLAY THE GAMES!!!