So, this is a good book, to get this straight right away. It's well-written, the stories are off the beaten path of generic fantasy. Their grittiness reminds me of stuff from the Warhammer universe, lacking completely any sort of pink elven shininess. Sapkowski occasionally borrows from common fairy tales and other well-known material, but he does so in an entertaining way, that strangely fit this world.
However: If, like me, you played the games, saw (at least some of) the TV show, this might well be less enjoyable. Practically everthing in this book is stuff that has "happend" in other media. It's kind of nice to get this "oh, here's where it all comes from" feeling, but it also means that really nothing is fresh. Still, it was a decent read.