And to those who play the Witcher 2, how does Skyrim compare to it?
If W2 is an open world, Skyrim is an open universe. Skyrim also doesn't have, chapters. You can go anywhere and do anything and go back whenever and wherever you like. The leveling/ability system is far less constrained, or less focused if you like, and the crafting system is completely different.
The combat is different as you can't parry, dodge, spin, thrust... But the game is more about exploring the world and your character than about spam rolling and flank attacking.