If you've never played a Trine game before, you're in for a real treat with Trine 2 because it's a very well-made game. Unfortunately, if you have played the original Trine, aside from the gorgeous visuals there really isn't anything new to the gameplay. In fact, in many ways I think they made the experience slightly worse by removing some features from the original Trine. Now, the Wii U version will include the as-yet-unreleased Trine 2 expansion DLC with more levels and character abilities. However, I doubt those new abilities will be useable in the original levels because they'd probably break the game.
But yes, definitely check Trine 2 out if you're curious. Hopefully, Nintendo will put a demo up when the Wii U launches.