Had trouble even launching the game because my antivirus program seemed to dislike The Witcher 2. A reinstall solved the problem.
I'm still not done with the prologue, but here are my thoughts so far:
The graphics are great, and the design is good. Great texture work and lighting. Animations are very well done. The writing is good so far and I have no complaints about voice acting yet. The soundtrack does its job. Didn't think about it much.
The only bad thing so far is the way they introduce you to the battle system. Not from a story perspective, but from a gameplay perspective. Died about 5 times in a certain area. Once you learn how to actually fight it gets better. Mixing signs with strong and quick attacks. Evading(blocking) is fairly easy, but I never used dodging so far. I am not completely comfortable with the mouse and keyboard, so I might play with a gamepad. It feels like that's how the game was designed.
Overall a very positive first impression.
Also; playing on medium.