Arthur's Spiderwick's Field Guide to the Fantastical World Around You, by Tony DiTerlizzi and Holly Black
This book is the actual field guide that they talk about in the Spiderwick Chronicles series. I think it is weird that the Grace kids went into so much trouble to hide the book and now it is being mass-produced! This book is about all the weird fantastical creatures that Arthur Spiderwick studied. It has labeled illustrations and lots of pull-out pages. In The Spiderwick Chronicles, the Grace kids saw many of these creatures, but they didn't see most of them. That is why this book adds a lot to the original series. This book is worth reading and keeping.
Care and Feeding of Sprites, by Holly Black and Tony DiTerlizzi
This is a book about how to care for sprites, which is really funny because... um.. you know... they don't exist. The pretty much only good thing about it is the poster. There is a fold-out poster on the dust cover. It is also really fun to have specifics of different kinds of sprites, not just the 10 words, "There are many different kinds of sprites in the world," which is about all Arthur's Spiderwicks Field Guide says. It is also fun to read how the author doesn't give a hint that sprites don't exist. This book is worth reading, but is only worth keeping if you: 1) want information on specific types of sprites, 2) want the poster, 3) believe in sprites, or 4) all of the above.
The Chronicles of Spiderwick, A grand tour of the enchanted world navigated by Thimbletack, by Holly Black
This book is Thimbletack's scrapbook of things he collected as the years went by at the Spiderwick estate. It is a sort of guide to the Spiderwick books including a map of the house, a family tree, and lots of interesting stuff about the people who have been there. This includes things that are not in the original series, like graded homework essays by the Grace kids, newspaper clippings from around the world, letters, pages ripped out of books, diary entries, and family pictures. It is fun to see how all these extra bits fit in with the original series, and it answers some questions you may have had when reading the series. For example, how did Aunt Lucinda convinced the sprites to come? This book has the answer. The Grant Tour book is worth reading, and worth keeping if you are a big Spiderwick fan (e.g., me!).
Notebook for Fantastical Observations, by Holly Black and Tony DiTerlizzi
This book is full of fun stories and activities organized by magical creature, including dragons, brownies, and lots of other creatures. For example, under dragons, there is a page for
"Sketches for two locations where dragons may be found, in the real world and in the fairy world." Some of these activities are easy to complete, others may leave you stumped, such as (under Brownies),
"I imagine this creature helping me with chores around my house." This book is definitely worth reading, but only worth keeping if you are willing to do the activities, like me. It is a good way to keep the fantasy going until the next series comes out (and, I assure you, it eventually will).