As someone who cares a lot about both Sapkowski's books and the video game series, I was anxious to see how this adaptation would turn out. I am glad to say that the end product is pretty fantastic. As most have already said, the casting for Geralt, Yennefer, and Ciri is perfect. Jaskier and Calanthe are also standouts The complex storytelling and themes of the books is preserved. And when the action scenes land, they are push the boundaries of what we have seen on the screen for this genre. The cinematography and color are better than they have any right to be on a TV show. Also, the soundtrack takes cues from the games while still managing to find its own sound.
In particular, episodes one and three in particular are among some of the best hours of television I have seen. A lot of comments I have hear state that these episodes were slower than the later episodes, but I think that this is because newcomers are still adjusting to the characters, lore, and timelines. If you are already familiar with the themes in "The Lesser Evil" or know what a Striga is, well you are likely to be blown away (though in that case you have probably already finished the season).
To be fair, not everything here is perfect. While the effects in certain scenes are absolutely fantastic, this is occasionally at the expense of other other moments (Torque probably suffers the worst injustice). Likewise, the combat in some of the later episodes doesn't feel as thought out or boundary pushing as in earlier episodes. Also, while the nonlinear narrative of this season work, I think a few decisions regarding getting Geralt and Ciri to meet as well as the stand at Sodden Hill were not the best choices compared to what is in the books. These, however, may be more of my critiques as a fan of the books, and not as relevant to those who are coming to this world for the first time through the show.
As I think about it though, while having a perfect first season would have been great, I remember when I played the first Witcher game many years ago it had its fair share of flaws even though I ultimately loved it and it paved the way for two superlative games. So, my final score would be closer to 4 1/2 if I am assigning a score while being objective (I don't think Google does half stars), but that is still great, and I am hoping that future seasons can reach 5/5 for me.
All of my criticisms are pretty minor in the end, and the overall experience is faithful to its source while still finding its own voice. I am not sure how so many critics are dropping the ball so spectacularly on this show, but I just hope the positive viewer response convinces Netflix to continue to put time and help this series to grow, much like the games did.