That is super cute! It's going to make a great keepsake.
Last trip we had the girls decorate individual foam covered books with their names, stickers, etc. as autograph books. Of course, our first morning in Disney I left Em's in the hotel room, thus having to purchase an autograph book from the gift shop right inside MK. I then had to stick with the purchased book for continuity purposes. Mother of the Year over here.

The ultimate plan is to paste the autographs into a scrapbook along with pics of the characters...doubt it will ever happen, though!