As a Christian, I avoid any fictional Christian literature because the books that I have read are boring, preachy and just not interesting. It seems the arthors don't want you to think, just accept what they say as fact.
My wife and her friends are into Christian lit to the point they shun things that are not labeled Christian. I find this attitude to be close minded, much like the books that are labeled Christian.
I do like the Narnia books, but I didn't know they were Christian when I read them years ago. I didn't find them preachy, just a good, imaginative story.