The recent movies The Lion, the Witch, and the Wardrobe, and Prince Caspian have stirred a renewed interest in the novels written by C.S. Lewis, of which there are seven. Before the movies came out, I had only heard of the Narnia series in passing, and to be honest, I wasn't particularly interested in it. After I saw the first movie, that changed. After the release of the second movie (with a surprise and horrible ending), I was interested enough in the series to read it for myself (the same thing happened with the Lord of the Rings Trilogy, but I was so exhausted after reading Fellowship of the Ring that I never finished the Two Towers). So I read it.
Unfortunately, even though I liked both Narnia movies, they really didn't do justice to the books. Too many things were changed, and in the end, the entire magical feeling about the stories was gone. This was especially so with the end of Prince Caspian, which was not only not true to the books, but there was also a question of the morality that the movie was portraying, which is something far more serious. Being stories on their own, the two movies weren't that bad - I thought they were thoroughly entertaining and certainly better to watch than most things that have been coming out lately - but they should definitely not be thought of as in any way conforming to the masterpieces by C.S. Lewis.
One can't read much of his work without getting the impression that he was passionate about religion. It is unfortunate that he never did become a Catholic (officially). However, as distinctly represented in his writings, his views could only be considered Catholic. As a Christian, he was certainly more faithful (and more Catholic) in his beliefs than most Christians are today, and probably most Catholics, too. Through this he has found more respect with me personally than any other non-Catholic (I've heard of) since the dawn of the Church.
However much they are children's books, they are also adult's books. In a world where there is too much pressure to live day-by-day, in the moment, troubling ourselves with the tasks at hand, we often forget about the things that really matter.
With that in mind, C.S. Lewis did a masterful job. The first book, The Magician's Nephew, starts off with some (probably not entirely innocent) childish mischief, but by the end of the book we're introduced to Aslan, Who can only be God, the land which He creates, called Narnia, and the "evil" that is present from the very beginning, which turns out to be none other than the White Witch, who steals the spotlight in The Lion, the Witch, and the Wardrobe, and is ever-so-briefly alluded to in Prince Caspian.
By the end of the book series (which I read in chronological order, rather than the order in which they were written), I was completely happy with the underlying morals and theological implications. I'm not afraid to admit that at the end I shed a few tears of joy for the characters upon reaching their final destination, and sorrow for the one character who was not able to join them.
If you haven't read the series, you need to. No matter how old you are, the Chronicals of Narnia present a timeless masterpiece of good fiction that is relevant to both children and adults.