I have not read the books or played the game. As a stand alone piece of drama its doesn't hold up. It is a unique world and there are a number of characters with potential. However, the storytelling craft just isn't there.
The show jumps all over the place between storylines and often the actions and evolution of characters seem totally random. Without motivation and the context of events shaping the characters' narrative it is hard to understand what and why they are doing. The result is a TV show that seems to lean heavily into standard fantasy tropes without taking the time to establish characters and build their arc within the created world.
Honestly many of the five star reviews are from people who were already fans of the books and the games. If you read between the lines of the overwhelming majority of reviews here they praise the choreography of fights, casting, cinematography etc as if all TV/movies were just sum of all these parts. The individual qualities are praise worthy but don't carry over the finished product. And appealing to the idea the the show is non-linear doesn't cut it either, if viewers don't get the structure of the plot line then this is a fault of the writing. That is just too clever by half. Storytelling hasn't really evolved since the days of Shakespeare, it doesn't really matter the medium or the presentation: ultimately stories are about how people respond to and grow in the worlds they find themselves in.