[Disclaimer: I got this book via LibraryThing's Early Reviewer program]
I am not really sure if this book could be useful to very young children (its target). The illustrations by Liuba Syrotiuk are very nice and colorful, and I am sure that the children would love to see and touch them - my ARC is a pdf file, which is good for review it but not to use it. What I feel lacking from Justine Avery is a way to explain children why (and how...) they can think outside the box. For example, what does it mean "slowing down when everyone else is rushing around"? A more sensible advice could have been "before rushing, stop and think if there is some other way to do one thing". Even the (sound) advice "It's always being proud of your mistakes" is followed by "Because they are just as valuable as every time you get things right", while I would have expected something like "Because next time you will know what not to do". I understand that a child cannot be given hard rules, but there could have been some more guidance.