Pauline Baynes, the original illustrator for The Chronicles of Narnia, was hired to take her black and white internal illustrations and create color versions for the new editions and they turned out really well.
(Click to enlarge image)
Printed on high quality thick bright paper the books are just gorgeous. Well worth the money. Especially considering you can get the box set from Amazon.com for only $35.09 with free shipping.(as of 11-15-2010). Talk about a steal.
I have one word of advice however. The publishers have re-ordered the books into chronological order. If you've never read The Chornicles of Narnia before I do NOT recommend you read them this way. There are certain things that take place in "The Magician's Nephew" that spoil events that occur in the later books. You are much better off reading them in the order they were originally written.
1. The Lion, the Witch and the Wardrobe
2. Prince Caspian
3. The Voyage of the Dawn Treader
4. The Silver Chair
5. The Horse and His Boy
6. The Magician's Nephew
7. The Last Battle