As someone who went 1 -> 2 -> 3, I can't say for sure, but I think you'll be fine. You're not wrong that you'll get more out of the game if you've read any of the books or played the other two games, as the game has plenty of recurring characters and references to them. Additionally, the love triangle between Geralt and the Sorceresses' in his life takes on more meaning if you're familiar with Geralt's past with Yennefer or experienced the story of The Witcher 1 & 2 alongside Triss. The main story in The Witcher 3 is a more personal tale than the story in the first two games, so it'll help if you brush up on some of the characters and events through some internet resources first, but I think you'll still enjoy it stand-alone, albeit less so than if you played the other games.