Some time ago, I published an article defending the Christian principles, analogies, and allusions present in the Harry Potter novels. I wrote that despite the conclusions that people may jump to, this alternate world of fiction actually brings to light many biblical philosophies; the novels even have references or parallels to biblical events, which in my opinion shows that the author was (at least) not trying to attack Christianity.
Recently, I was visiting with a friend of mine about this article and my (somewhat passionate!) beliefs about the usefulness and innocuousness of alternate worlds in "other-world" fiction series' today. My friend, who has a background working with deaf children, could not read the novels with children who are hearing impaired. These kids she worked with have difficulty separating the actual from the imagined, making literature involving other worlds completely inappropriate for them. I had never considered this before.
Perhaps this genre is simply best read by those who can separate fiction from reality, or perhaps we're comparing apples to oranges. I'm not sure, but I definitely took something away from this conversation; I'm sure it will take me a while to figure out just what it is.