Just finished up reading Books 6 and 7 of Narnia aloud to Sam. Just some quick observations:
-- The Magician's Nephew is surprisingly funny.
-- The Last Battle is ... not.
-- There's a point where an animal dies during the Last Battle that is just so sad that it snuck up on me and choked me up. Lewis was walking quite a line here, in that he was writing about death for kids. I tend to therefore give him a break when my own 21st-century sensibilities think he went a little too far one way or another. One thing about the story is that it certainly moves right along, too.
-- Speaking of balance, you shouldn't mention the depiction of Emeth without the depiction of Tash, nor the depiction of Tash without the depiction of Emeth. Either character by itself is incomplete, you need both, and be skeptical of any critic or pastor who quotes one without the other.
-- The Last Battle becomes a lot better of a book if you don't take it as allegory, but if you take it like Lewis insisted you should take it, as a story of God at work in a different world in a different way. In a world in which God's son is manifest as a lion and physically present, then a deception can be built on that manifestation to destroy and corrupt. Interesting to think about what that means for why God seems so invisible/distant (to modernists, at least).