The games definitely elevated the book material. I read the books after putting in countless hours in TW3 (hit platinum on the PS4) and the way they described the characters in the books perfectly lined up with the games. Triss having the bright red hair is a slight deviation but I think it works perfectly for her.
I'm on the fence about this because the teaser hasnt done anything to give me hope, and I agree with the issues others have brought up (Dryads looking like they're from Wakanda, Ciri aged up, Triss looking awful, Nilfgaard scrotum armor, etc), but man do I wanna be wrong cause I was so stoked for this.