We listen to audiobooks as a family on our long drives. We've listened to one other Brandon Mull series - The Beyonders. This is the start of a new series that is now at book 3, and is scheduled to run to 5 books.
Overall, we all enjoyed the book. It is similar to The Beyonders in a lot of ways - children finding their way accidentally to a magical world that is under the thrall of some sort of evil king who needs a good deposing. There is magic and mystery and mayhem and noble boys and plucky girls. It really is good fun.
However, one problem with the book is that it really runs out of steam near the end and there is a long, dialogue heavy, expositive sequence that sort of sucks the life out of the narrative. It doesn't tie up the ending, but when I select a multi-book series to read, I don't really expect each book to necessarily end with the loose ends tied up.
We will continue the story soon!