My 4 year old son got this book in a party bag so I didn't look at it before reading it. I sat down with my two kids 2 & 4 yrs and read it to them. I was surprised at the tone of the book and found myself very quickly having to change the language used into more child friendly words. The first page reads "You're swimming in the warm blue sea. Whats the one word that turns your dreams into a nightmare? What's the one word that makes you think of a giant man-eating killer? Shaaaarrrkk!" Further on in the book it goes on to say "And then when they are close enough for the kill, they feel the crackle of their prey's living nerves, so they bite in just the right place ... no matter what the prey! Wheather it's plankton ... or people! Oh yes, it's true - some sharks do kill people; about six of us every year."
I personally thought this kind of graphic language and the use of such strong words unsuitable for my small children. I didn't want them never to dare to go into the sea again! It is a shame as there are really good parts to the book, my son really enjoyed looking at the different sized sharks and learning their funny names.
My advice would be to read it first, it may well not scare some smaller children but in my opinion it's suited to an older age range than the front cover suggests.