I do not really care how similar it is to the books or the games; it is just that the actors are good, the characters are charismatic(not all of theme but most), and the story (and sub-stories) is interesting but somewhat difficult to follow probably because of the high frequency of strange words unique to the Witcher univers, but also to the parallel stories of several protagonists; the story being set in two different time periods doesn't help either.
The Witcher is receiving bed press probably because it is being compared to GoT. this was predictable and inevitable, but the audience will like it.
It is one of the best medieval fantasies I have seen in a TV series format.