Season 2 is a good fanfic. Nothing more. But it doesn't have anything in common with books. Whole story was drastically changed. Have massive plot holes, non-existent logic and bad world building.
Characters are totally changed in way of thinking and motivations. They are written with half deph and half brain power of their books versions.
Character creation and looks are completely missed with source - books in most cases.
Actors made a good job. Henry as Geralt is perfect.
Visually season 2 have really great shots. Locations are great, cgi is very good and overall visual quality is 5/5. What brings this down is a story. If it was named "The Witcher - unknown stories" or something like that and didn't called adaptation, I would give 4/5. First season was good, like 3.5, maybe 4/5, but season 2 is complete failure in terms of story imho. 2 stars, because at least it looks good visually.