This was a very good addition in which significant things really do happen. Books 7, 8 & 9 of this series are causing some growing pains. This book helped with those, however, there are still some issues with this entire series.
When you are this far in and everyone has changed species once or twice, not to mention their name, and you've got 8 previous books of history and characters from a completely different book series joining in, the reader has an awful lot of baggage to carry around. After book 7, I didn't get the next one because I was overwhelmed. I actually reread it before starting book 8. That helped a lot as I was able to get myself grounded again. I was able to remember who was perhaps a whale a few books back verses being a spider or a tree.
OSC once said that as an author everything you mention in a book is picked up and carried in the reader's backpack. So don't mention something like a Volkswagon Beetle, unless you are going to reward them for carrying the weight of that in their backpack for the length of the book. At this point in the Artorian's archive, we've got a few beautifully connected and well organized freight cars of items coming along behind us. And even though everything in those cars IS likely to be mentioned again as a "reward", I must say that the load is getting a bit heavy.