I agree about
The Lion, The Witch, And The Wardrobe. I re-(re-re-re-)read it before seeing the movie and was pleasantly surprised to see how much of it survived the transition to screenplay intact.
Caspian, on the other hand, didn't feel like the book - I don't know how better to describe that. I'm only guessing that one of the problems with
The Voyage Of The Dawn Treader is the enormous difficulty in translating it into a screenplay -
The Odyssey has already been done numerous times, after all. And how in the world to end it satisfactorily? What Lewis added to the Odyssey were the most overtly Christian set of images in any of the books except perhaps for
The Last Battle: the redemption of Scrubbs, the appearance of the Lamb, and Reepicheep's choice to continue to seek Aslan's Land in the only way it may be reached. And, of course, Aslan's own statement to the Pevensie children that He is known by another name in their land and that the point of their presence in Narnia was to enable them to recognize Him.
Personally I found that a very satisfying ending but as literature it is far from the light, allusive touch in The Lion, The Witch, And The Wardrobe. For persons unacquainted with Christian symbology it was likely to appear incomprehensible; for those hostile to it the thing would have been shrieked at as heavy-handed propaganda. In short, I think of all of the series except The Last Battle it might have been the most difficult to translate into a multi-leveled screenplay.
Not so The Silver Chair, a much simpler story that is, IMHO, eminently filmable. But of all of the others I'd most like to see someone film The Magician's Nephew. It's blatantly Genesis - Digory is even tempted by an apple - but done with the same light touch of The Lion, The Witch, And The Wardrobe and working perfectly well on the level of a simple adventure story for those who find the Christian allusions distasteful. And that, unfortunately, describes a significant portion of the movie's market. And, of course, for those of us who did love The Lion, The Witch, And The Wardrobe, it explains so very much, so very well.
The Magician's Nephew would be perfect -- with all that Victorian London . . . "in those days Mr. Sherlock Holmes was still living in Baker Street, and the Bastable children were looking for treasure in the Lewisham Road . . . "
And Jadis -- what a villainess for the screen!