It's definitely above average, better than most fantasy themed shows of the past few years, but people should stop comparing it to "Game of thrones" (GoT). The plot, the writing, the depth of characters, the overall sense of realism of the world where it is set, put GoT to a completely different league.

In terms of story, I guess that people expect different things from the two. GoT emphasizes more on the moral and political questions that arise from the circumstances and the plot, and in that manages to go beyond most works of fantasy, making it more relevant to the viewer's reality. The witcher exploits, at least so far (I admit not having read the novels), more "standard" themes of fantasy literature, and adopts a more simplistic worldview.

I won't go into details, many things have been said about the two. For example some reviewers praised the choreography of the fight scenes in the Witcher, saying that GoT could have benefited from a similarly good choreography. To that one would answer that the gritty realism of the early seasons GoT fight scenes is what the witcher really misses.

Don't expect anything near GoT production value. Some people mention that the Witcher was actually more expensive to make. That alone is never the measure of a good show, nor can it ensure production value, nevertheless it's certainly worth watching (and we can probably say that it is worth its cost).