I was at one of our local Barnes and Noble stores in Lansing, Mi the night the latest Harry Potter novel was released. The store was packed with kids and parents excited about the midnight release of the new book. I've never read any of the novels, nor will I probably.
I have heard Christians express concern that the Harry Potter books are harmful to kids because they promote magic of the ilk that the Bible speaks against.
Radio Bible Class, a conservative Christian ministry in Grand Rapids, MI cautions against over-reaction and talks about the value of this series that has kids reading again. They see value in the stories and they see value for those who read them.