I've read and listened to several of the 39 Clues books, and I knew these books would be similar to a degree, so I wanted a taste of the series in order to be able to book talk it better. From the start I could see why kids like these books. They move along at a good pace which is always important for keeping kids reading. Plus there are a variety of characters, so if you don't like one main character you may like another (My personal favorite was Abeke). I also loved the animal aspect! Any kid who loves animals will really like that part of the story. I think my favorite animal was the panda just because Meilin wasn't real thrilled to have it as her spirit animal!)
As for the rest of the story - it was good. Lots of action and suspense so it kept me listening. I know kids will enjoy that and want to keep with the series to see how it all works out.
Final Thought: Well done and perfect for the middle school kid. Action and suspense enough to keep a reader awake but not enough to scare them!
Of course I would have this book/series in the media center. It's a great series to hook the 39 Clue readers into. But will also appeal to kids who liked Gregor the Overlander, The False Prince or maybe even Percy Jackson!