A friendly warning to readers: Even though "The Way to Write for Children" is very precise about what SHOULD NOT be in children's books, it is quite the opposite about what SHOULD be in them.
On the very first page of the text, Joan Aiken bluntly informs readers that "there is no _one_ way in which to write for children." In another chapter, she explains the futility of dividing child readers into age groups and trying to target a single age. Throughout the book, she gives examples of what she considers poor children's literature--and not without good reason.
Aiken is not a writing teacher who says, "Do this and this and this, but not that." She is more like a mentor whose gut instinct about these matters is so finely developed that she can tell what will work and what will not, even though she may not be able to explain why. Yet she does try! Those who like their writing manuals well organized into clean-cut sections and subsections will not appreciate her attempts, but those who understand that she is truly sincere may dig deeper and find unexpected treasure.
You'll enjoy this book more if you have read as much children's literature as Aiken has and are familiar with the authors and titles that she liberally "name drops" throughout the text. I bought my copy three years ago and understood about 10% of it. Then I started studying some of the books she used as examples: "Daddy-Long-Legs", "Poems of Childhood", "The Chronicles of Narnia", "The Hobbit", "I Am the Cheese", etc. With that, her words took on new life for me.
I can compare reading "The Way to Write for Children" to listening to a wise and remarkable friend speak--but not lecture--about children's literature. It is definitely not writing school, but the education I receive is superior.