This will be a slightly informal review as this is a short story. But I won’t skip the rating so no worries there.
This is meant to be a spooky adventure and I think for children it would be (I can totally imagine this being read to them and having to do voices and it works for the creepy/scary factor quite well). And of course it is but a short story, placed between books.
One of the things it does very well is to make you want to read the next book, as it hints at things to come that they discover in this particular cavern. (I definitely want to know more, but to say what about would be to spoil this story).
The pacing is fast and it still covers a kind of recap included in the story, just in case you have read the books a while ago and don’t remember everything. Trey and Badger were very happy to see that Orgo and Gugubats are still part of the story, even in this short one, so they posed alongside the book, eager to please.
[In case you haven’t been following on twitter, Trey is the Orgo on the left of the picture, and Badger is the Gugubat on the right holding the book. A group of us post pictures of the adventures of our little Orgos (and gugubat) with the tag #iwantanorgo #orgoadventures which you can follow if you’re curious].