I picked up this book expecting it to feel like an analogue for flipping through a modern-day wikia page. I have to say I was pleasantly surprised.
I describe this book more as a guided museum tour. There are a variety of wonderful images, diagrams, and icons that catch the eye, all complete with various captions, descriptions, and speculations should you wish to know more. These texts are especially immersive because they treat the world as real—each blurb treats a species, text, or event as something that exists, and many "research notes" are written as speculative, as if the writer is trying to interpret the world of Thra for the reader but hasn't uncovered all of it. This gives the reader a feeling of truly taking an educational journey through a fictional land, while withholding just enough information to keep it wondrous and mystical (pun intended).
On that note, readers will be happy to know that—old as this book is—it is considered canon in the Dark Crystal universe. The foreword indicates that its purpose is to share all of the wonderful behind-the-scenes concepts that didn't make it into the film. As a result, it does a wonderful job of enriching the world we already know and love with actual substance, without feeling like a superfluous marketing ploy to prey on nostalgia or on their fans' wallets.
A self-described "coffee table book," this didn't warrant finishing. I opened it up one afternoon with a cup of coffee and flipped through it, stopping to read the detailed descriptions and faux-historic blurbs for a few minutes at a time before skimming to the next feature that caught my eye. Next time I get the chance, I would gladly put the smartphone down and spend a short break looking through this book again for a gem that I missed last time.
I would recommend this book to any The Dark Crystal fan who is looking for a deeper dive into the world as intended by its creators. Buy it if you can; it's a wonderful thing to be able to return to when you have the time.