I thought the Witcher I and II were quite masterpieces (and they still are, in their own way) - but the third game is just mindblowing. Emotionally strong and intriguing main story, interesting side quests that don't feel like tedious sidequests in some other games, breathtaking graphics, exciting, strong characters - I don't exagerrate it when I say - be ready for an adventure of a lifetime as Geralt of Rivia :)