You approached it as far too much of an adult. Lewis wrote it for children and to enjoy it, one must become as a child in some ways.
I read the books as a kid and HATED them. Later, in my adult life, I read more of CS Lewis's works and then re-read the Narnia series. LOVED the books as an adult.
Thought the movie was well done. I was quite fearful that they'd totally hack the book, but they did the story justice.
His Chronicles of Narnia is for children (although adults can enjoy it as I did). For adults, he wrote the space trilogy. It is equally chock full of Christian metaphore, which is EXTREMELY unusual in science fiction.
Don't know what this is all about. My two daughters, both 30 and over, and I attended the movie in a mood to enjoy it and thought it was wonderful. All of us had read the book.