The Witcher 2 continues the story, so it might be a bit jarring if you haven't played the first one. Then again, the first one was pretty jarring, since Geralt's lost his memory.
The controls are very different. Combat in the first one involves pausing, clicking on your target and timing your attacks. The second one takes the more conventional "press X to swing sword" approach.
That all being said, The Witcher 2 looks significantly better on PC. Assuming you have one that can handle it.
...wish I did.