This is the book the popular videogame "The Witcher" was based on. I haven't played the videogame, so I can't say how similar the game might be to the book, but my guess is 'not so much.' However, I can see how the book would lend itself to such a conversion, because it's written in an episodic format - different adventures loosely tied together. The Witcher Geralt is a man, but one trained and treated from youth for his profession of catching and killing supernatural monsters, until he may have near supernatural powers himself. But in a world where fewer and fewer monsters plague the land, Witchers may be a dying breed as well. This makes for a nicely angsty hero, but there's still enough for him to do in his mercenary-like lifestyle to fill up some quite entertaining stories. Most of the adventures refer in some way to traditional legends and fairytales, but with surprising twists.
In a few places, the language is a bit awkward (probably a result of the translation from the Polish), but overall, this was a very entertaining, and sometimes thought-provoking fantasy.