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 think the important thing is to READ them, though.
My kids still quote scads of dialogue from the book (after 50 years, I have all seven almost committed to memory). We were skiing on a BSA Venture Crew trip when my daughter came hauling down the slope, skis parallel, screaming, "Beware! Beware! Beware! The Bolt of Tash falls from above!" Of course she wiped out, and I skied over to the snow-covered heap and inquired, "Does it ever get caught on a hook half way?"