See tbh I have dipped in and out of this thread having had no part in the Witcher franchise at all throughout the past few years - I too really thought this would be a stinking mess because I've never actually seen a decent game adaptation (even though this is a book adaptation, I know).
I thoroughly enjoyed it. I started playing The Witcher III in January, then I decided to watch the Netflix show a few hours in. I honestly think Henry Cavill nails Geralt? And it was interesting to me to find out that he actively pushed to get this role because he already loved the story and played the games etc:
I can't help but feel a bit shitty for him now with all the vitriol that was spouted in the lead up to this release. The reviews are pretty decent, but I think importantly the fans have done a complete 180 on Cavill as Geralt since this came out. I genuinely think he does a good job, and I really enjoyed the first season. If nothing else it gave me some neat backstory while playing Wild Hunt for the first time.
I feel like we're maybe all a bit pre-disposed to go "eugh no don't touch my stuff" when it comes to the media we like but I'm a total outsider in terms of the Witcher fandom so maybe my opinion counts for shit in that regard. It did look shit at first, with that pre-production screen test shot of Cavill as Geralt and stuff.
The main thing that is an issue in the first season is the unexplained time skips all over the place. It's not obvious unless you're really paying attention, and there are some choices that lead to inconsistencies (some characters don't age and they shouldn't, some characters don't age and they should) and the only reason none of that bothered me is because I went in having read a review that explained the time jumps properly. It was a weird choice to not even have title cards that say "X year" to at least indicate we're jumping backwards and forwards in time, but it's coherent enough if you know that going in.