I commented on a blog that criticized Neil Gaiman's "The Problem of Susan" which is a critical look at the Chronicles of Narnia. Here is an excerpt of her argument:

"“The Problem of Susan”, to me, is a whole different question. It’s not an assault on God; it’s a specific, personal assault on one specific person’s affectionately rendered depiction of his beliefs. C.S. Lewis wrote Aslan to reflect his experience of God, and as I’ve said, that man loved God like nothing else. Whether you agree with him or not, he wrote Aslan with such absolute sincerity and love. I think it is unkind to take such an honest expression of someone’s religious devotion, and do this with it; no matter how much you disagree with him, or find his beliefs about women/God/whatever, to be damaging. It makes me feel all yucky to read this part of the story – a reaction I don’t think I’ve had to something I’ve read since this horrible book I got for my eleventh birthday, the contents of which I don’t remember at all, but which upset me so much I hid it under the couch and still couldn’t sleep knowing it was in the house so I got up and threw it in the trash and poured wet coffee grounds on top of it."

You have a legitimate argument, Jenny. I agree that the dream is disturbing, but I think that was Neil's point. (He admits that in the introduction after explaining his bout of meningitis.) The story was deliberately irreverent because Neil wants to remind everyone that Narnia is, at heart, just a story. At the same time, it shows the power of children stories, especially with the Mary Poppins dream. (I know what you mean about horrible books, though. The first Sandman volume made me feel the same way. Twilight made me feel that someone had taken what could've been a great book and chopped the ending into firewood and hamburger meat.)
"The Problem of Susan" is more about security, or the loss of it. Susan as an adult no longer feels secure concerning God; that's why she dreams of Mary Poppins, who is the ultimate form of security. She rescues the Banks children from constant mishaps and manages to keep the household running and stable, even when she leaves.
That said, I think the story could have been done better. It's like the Graveyard Book could have been done better with the plot. But I keep rereading both of them because Neil's style is freaking beautiful, sad, and addicting.
We should email each other. This was a fun article.