This is a review of the series moreso than this book.
Beyond the Spiderwick Chronicles is, at first glance, basically the kind of sequel you'd expect. It takes the themes and ideas of the first Spiderwick series and revisits them with a new cast of characters. So again, we have kids who discover the hidden magic all around them, by gaining the ability to see the fairies and other assorted magic creatures around them. And they also get involved in a big adventure, that involves having to save people from the creatures that - to everyone else - are essentially invisible.
But for the sequel series, the authors tried to mix things up a little. Family backgrounds were changed: instead of a family on the brink of divorce, we get a blended family - Nick Vargas and his new, fairy-obsessed sister who just got introduced to his life. The setting is different: the woodsy small town is replaced with the Florida beach. And, perhaps most controversially of all, the threat is replaced: sentient human-like goblins are replaced with giants and wyrms, who have the intelligence of a typical animal, but are threatening just the same.
One of the things I liked about the original Spiderwick series is the constant looming threat of the ogre Mulgareth and his army, and what they might do to the kids as they try to get their MacGuffin... er, book. All the threats they encountered were intelligent life forms - goblins that locked kids in cages and wanted to eat them, dwarves who captured the sister and put her in a sleeping spell, and the shapeshifting ogre who ultimately came after the entire family.
But in Beyond the Spiderwick Chronicles, the primary threats are animalistic. The giants just stomp around and react to specific things, unintentionally damaging the world around them, hence they must be stopped. The wyrms have their own animal-like behavior, and they cause havoc without consciously knowing what they're doing. Basically, it's like taking a story of someone who has to evade a kidnapper, and deciding to write a sequel where the person has to survive an earthquake instead. The change is almost that drastic. Human vs. magic humanoid becomes human vs. magic nature.
But most of the classic Spiderwick elements still remain. Mermaids and boggarts still exist, and are still sentient and show human-like desires and pose their own unique threats. The characters still have to use brains rather than brawn to survive, always to me the defining element of an adventure. And the mix of adventurous storytelling with fun character interaction and real-life elements continues just as before, and done just as well as in the first series.
One thing does bother me a bit, though, and that is the enlarging of the cast. In the first Spiderwick, the kids were mostly acting on their own, though with some magical help and a brief chat with two adult mentors who, for their own reasons, cannot actively help them. Here, though, the kids gain direct help from not only the main characters of the first book series, but they even get help from the girlfriend of the older brother character, bringing in another outsider, and there's another adult mentor.
It is neat to see the Grace kids from the first book interacting with the Vargas family from this one, and I also liked seeing Nick's older brother introduce his girlfriend to the fairy world and get her help. But it's just not the same as with the first book, where Simon, Jared and Mallory Grace were on their own. Here, Nick Vargas has many supports he can call on, and does. In the end, of course, it's largely Nick's quick thinking that save the day, but it just wasn't quite the same feeling as when you have a smaller cast of main characters handling their own selves against a big threat.
However, even with these changes, I still liked the new series overall. The storytelling was of the same quality as the first, the interactions between the old and new characters were interesting and fun, and the change from "intelligent" to "natural" threat was actually handled pretty well, and proved to be just as devastating - actually, much moreso - as the threat from the first book series. In all, I'd have to say that Beyond the Spiderwick Chronicles is a worthy follow-up to the original Spiderwick Chronicles, and while I'm still not a huge fan of all the changes done, I think that overall, it was handled pretty well.