Some nice puzzles and the overall code is a good idea to keep the children engaged and curious.
I totally see this as a useful and fun puzzle book for during travels, quiet time, or something to work towards while on the beach.
Unfortunately, my son and I were not keen on the graphics and the fonts much, but the layout makes it easy to work on, plus this is a puzzle book. When the illustrations are very precious, you tend to get distracted or do not want to ruin the book. But perhaps, it could have been more balanced in that sense. I admit that this is subjective.