This WItcher fan is interested, but because of the developer, not the genre.
I think it will be a different experience, and I hope it will be so. Geralt in TW3 is a known character; he is someone we came to be familiar with through the books and the earlier WItcher games. So in our minds we expect the Geralt in TW3 to behave in a certain way, react in a certain way. Sometimes I apply the WWGD principle when confronted with a dilemma in TW3 - What Would Geralt Do - based on what I know of him from the books and the previous games.
V, on the other hand, is a blank slate. You are free to play him/her in any way you see fit and it would not be out of place. For instance, Geralt would hesitate before killing a doppler or a succubus. An action like going full psycho and slaughtering an entire village (like Gaetan did) would be something Geralt simply does not do. And indeed, the game doesn't allow you to - you can't attack innocents. But with V we can explore the darker side of the protagonist's humanity (Geralt as a metahuman; V enhanced by cybernetics) and see where that takes us.
Most RPGs have us playing an inherently "good" person, out to save the world. TW3 offers a refreshing change from that trope - Geralt is out simply to rescue Ciri, albeit doing good things along the way. I do hope CDPR allows us to play a darker, more selfish protagonist in CP2077, looking out only for V.
