Just received the book and it's better than I had dreamed of. For one, it's a gorgeous hardcover edition that includes marvelous illustrations and a number of covers used for both Ninth Configuration and Twinkle Twinkle "Killer" Kane throughout its printing history. But the icing on the cake is that the book is a limited edition of 200 - each numbered and also signed by William Peter Blatty. My copy is number 20.
This is just amazing. I'll still keep my old paperbacks (so I can re-read the books) but this is truly treasure for the shelves. Thanks to the good folks at Centipede Press for putting this edition together.