well I think within the overall quest, it's original. I think the idea of writing a series of books that kind of explains the whole cosmic balance, and what not, is over done.
But I really do like the series so far. I am only about halfway, so you're right, I don't have much to base my opinion on. But I'm enjoying it. The first two books really kept me entertained... intrigued... I read through those pretty quickly. The third book was a bit harder to get through, in my opinion. I even thought about taking a break from the series, which generally translates into not finishing it, for me.
So far the fourth book seems pretty good. I think now, I just need to find a nice quiet place I can read. My dorm room isn't really providing me with a good reading environment at this point in time.