When MacMillan reissued the books in the U.S., back I think in the 80s (with new illustrations by Pauline Baynes), the American publishers changed the order to Narnian chronology instead of the order in which the books were written.
The problem with that approach is that Narnia grew as Lewis produced the books over a period of years, so that when you read The Magician's Nephew, there is much that you will not understand if you haven't read the preceding five books. It comes first in the reordered series, and I think that's a mistake because too much is assumed by the author, who thinks you've already read the others.
I read the whole series when I got the books for Christmas when I was 6 -- a long, long time ago (they had just been published as a set for the first time in the U.S. . . . < eek >) I wish I could read them again for the first time!
I just read it (Chronicles of Narnia) for the first time and I disagree. I read the first book as if it was the beginning of the story. Yes, there were somethings that kept me guessing but they filled themselves in by the end of the story. This is what kept my interest in reading the rest of the books.
I don't think you lose anything from reading them chronologically, in fact, I think I would have not liked reading them out of sequence.
I read all the books as a kid and loved them. I think the Silver Chair was the first book in the series that I read, only because it was a gift.
My wife is eager to read the books because she didn't read them as a kid, but LOVED the movie (hear that, BobJ?).
So for someone who hasn't read the books, in what order should they be read for maximum enjoyment?
I just read this website about the order. It's interesting.
http://www.aslan.demon.co.uk/narnia.htm