Lately, we've gotten used to series that have the same production value of big budget movies. The Witcher is more along what you would have expected a TV show to look like, albeit 10 years ago this would have been extremely good quality for a TV show.

Therefore it isn't bad per se. Actors, script and cinematography are along the lines of tv shows, not movies. We've simply been sploilt by ridiculously good, quality series lately.