The Chronicles are obviously not Scripture. But I would cautiously suggest that in them, one can take away some unique and new insights on the character of Christ (Aslan being the Christ character) and on human nature and the darkness lurking in the unredeemed heart, as well as the pull of the flesh on the regenerate heart.
I have learned a lot from them. Perhaps it is my shortcomings that made them helpful, but, even so, they are good.
I agree whole-heartedly. A tremendous amount of familiarity with Scripture and theology lies behind the Narnia books, and even though this learning may not always be openly expressed, it shapes what is there. You're getting two thousand years of Christian wisdom condensed into these little stories, and often have no idea when you read them what you're being taught and how--you only know that it "feels" right. Analysis comes later, if at all, and is not really necessary.
I have loved Tolkien's The Lord of the Rings ever since I first read it at the age of fifteen. It sparked my imagination, opened up a love of the natural world, and reintroduced heroic ideals into my life. But the Chronicles of Narnia fundamentally altered who I was. I could never have guessed, at the age of seventeen, somewhat shame-facedly looking at a "kid's book," that the earthquake was about to begin.