IMPORTANT: For U.S. customers purchasing the illustrated edition of Harry Potter and the Chamber of Secrets, you will notice the text has NOT been converted to the "Americanized" version of the original U.S. releases. This difference isn't as prominent or noticeable as it was with Harry Potter and the Sorcerer's/Philosopher's Stone, but still something to keep in mind. Also, to answer a question that has come up quite a bit, this is the FULL BOOK and not an abridged or shortened version.
The overall quality is fantastic. The colors are vibrant and the images are, in my opinion, even better than those in Harry Potter and the Sorcerer's Stone: The Illustrated Edition (Harry Potter, Book 1).
The best features: 1. Underneath the book jacket, the novel is bound in a sturdy orange hardback with green lettering on the spine. 2. The paper is thick with an eggshell glossy finish. 3. All chapter intros are illustrated. 4. Some images take up full pages or multiple pages. Most illustrations share the page with text. 5. Every inch of the book is illustrated or decorated in some fashion. There are NO white pages in the book. Even the pages without large illustrations have the paper printed and marked with ink blots or paper "stains". In Chamber of Secrets (compared to Sorcerer's Stone), some pages even have beautiful patterns over the entire page. One page has a spider-web pattern and is right next to a picture of Aragog. Quite brilliant overall.
I would highly recommend this for anyone looking to read the series (again, or for the first time), especially if you plan to read this with someone younger. Based on the fact that the illustrations for this book were even better than in the first book, I'm now looking forward to the rest of the series even more. Prisoner of Azkaban is next and I'm heartbroken it'll be so long before I get to have it in my collection.