As a fan of both the games and the books, this netflix series is better than I expected. However it is not without flaws. Despite these however it rises above them to establish this universe.
Generally speaking the visual effects are pretty decent. There is a mix of both practical and cgi effects. Some cgi doesn't mesh as well with the live action.
Swordplay is also generally decent. Though one could nitpick that all the twirling Geralt does leaves him open to attack. That said it is fantasy so its a bit easy to overlook this.
Costume design is also decent. The nilfgaardians or black ones have armor that looks absolutely terrible. It not only looks impractical but it undermines them being taken seriously as a real threat. A powerful army cant afford better armor than this? The Cintran and Temerian armor however looks great.
With regards to casting? Henry Cavill as Geralt, Anya Chalotra as Yennefer and Frey Allen as Ciri are fantastic. Even Joey Batey as the bard Jaskier (Dandelion) was a pleasant surprise offering up a damned catchy tune. Special note has to be given to the actress playing Tissia DeVries who also voiced Duchess Anna Henrietta in the Witcher 3 Blood and Wine.
Some of the casting I was less thrilled about. I am not quite sold on Triss Merigold yet. Hopefully we get more in season 2. I also have a bit of an issue with the race swap of Fringilla Vigo. Nothing against the actress personally. But in something like this which has nations and geopolitical elements. Changing a charcters race can also change their backstory. In the Witcher lore, people with darker complexions typically come from zerrikania or Ofir. Fringilla is a 2nd cousin to duchess Anna Henrietta of Touissant. She is a secondary character and maybe like Triss in season 2 or beyond we get more that cements her place in this role. Much like Samuel L. Jackson as Nick Fury in the Avengers.
Narrative wise this show draws from much of the short stories from author Andrez Sapkowski. This works for and against it. There is some time skipping and jumping between characters that could be a bit disorienting for newcomers. Its nonlinear storytelling. Stick with it and you will see things converge as you see similar scenes intejected with new one that offer new context and perspective. It all comes together in the end and will leave you wanting more.