This was a delightfully fun and easy read! The plot advanced beautifully and made sense, which many fantasy books don't manage to do. There was a lot of scientific explanation behind why the serum worked on the children and the stones, and it was interesting and though provoking. The reasons behind the invention of the serum were a little sad, but the book in general was light-hearted and amusing, which is exactly how a book about children with super powers should be!
I loved that Jessica and her friend Izzy worked together to figure out what was going on, and I cheered when Izzy got a power as well. The variety of the children who ended up working together are amusing (mean girl Heather isn't really mean at all), and their different powers are ones that many of us would like to imagine having. The parents don't get in the way but are around, Nancy is everything that a godmother should be, and even Max's distracted dad is wonderfully clueless-- that way, he needs the children to save his scientific work!
My only objection is that Kessler is a British author, and the US edition has clearly been scrubbed of British terms. I would love to see the British edition!
Has Anyone Seen Jessica Jenkins is perfect for fans of Kessler's Emily Windsnap series, Kate Saunders' novels, and E.D. Baker's fairy tale retellings. A great choice for readers who enjoyed Ruth Chew's books when younger. One note of caution: younger readers might find this book to be so believable and intriguing that they will concoct a serum in the kitchen and attempt to soak their mother's jewelry in it in order to become invisible just like Jessica!