First, you should read the first three books in the series, as it will answer a few “who are you” questions in Gilbert #4: The Island of the Orange Turtles by Art Baltazar. And second, this book is way on the “little kid silly side” and adults may not appreciate the “slap sticky somewhat less than intelligent antics.”
This story is cute, but not overly detailed. Gilbert and friends visit Sherbet’s island, where they meet all his siblings and new baby brother Bix (Because It eXists”), who is even more rare than Sherbet (who is orange with orange spots). Bix is such a rare orange turtle he is purple (yes, made lots of sense to me, too). There is a shark looking for the “rare orange one”, a seaweed creature name Todd Weeds (who has some groovy dance moves), and a Doctor/Scientist that might be a bit mad (no, really, they look really grumpy).
I am not sure I liked this book, but I see the potential for kids (ages five to young-eight). Gilbert and friends are meant for the early reader or the reluctant reader. It is simple and quirky. The lightness of the flow and tone will keep the reader moving along. This (if has not already been made into one) will be a great half-hour cartoon on Cartoon Network like stations. This is for the kids that like bold and bright colors, not necessarily a lot of traditional but the “quick action” of a book to tv show.