@Roz - Yes, plus the way she's described in the books, that actress honestly is superb. Yennefer is not supposed to be stunningly beautiful; it's her charisma and force of personality that draws people to her. If she and Henry Cavill have good chemistry, that casting was inspired.
Depending on where they start in the story, the actress playing Ciri might be a bit too old, but that's not necessarily something they couldn't tweak in the story. The actress for Ciri is otherwise spot-on for the book description as well.
Yennefer, Triss, and Ciri are all made more "cinematic" in the games; Triss, for instance, is not a redhead.
The books are really worth a read, though the English translation is considered lackluster compared to most. And though the final book of the saga takes a bit of a weird left turn into Arthurian myth and never really quite seems to resolve the Wild Hunt storyline it introduces. (Hence the "fix-it fic" that the Witcher 3 basically seems to be; where the first two games are in their own little alternate continuity, the third seems to take place within the book continuity, set right after the final book.)
At any rate, I think the casting is very true to the books. And I am certainly very happy it's an adaptation of the books rather than the games; as I think literally all of my friends who've discussed the Netflix series in my earshot know by now, I am hoping the series at least touches on the Korath Desert arc and Ciri befriending Ihuarraquax. (#GiveCiriHerUnicornBuddy2k19)