I have played the game through already as a Hard Paladin, and now I'm playing as a Hard Mage. The game obviously remains mostly the same, but there are several differences in terms of your strategy against the enemies as a Mage compared to a Paladin. Also, it's a good thing that the items are randomized, so that adds even more interest.
2 run throughs will be enough for me for one holiday period, however. I've got The Witcher: Enhanced Edition sitting here waiting for me to play it.