For those who have read Snuff, The World of Poo will have some meaning and reference. For those who haven't read it yet, it's not a pre-requisite. You'll enjoy this book regardless of your age and the humour IS aimed at all ages - the older you become, the more jokes you'll find and get!
You'll be able to read this to your kids (probably aged 7 onwards) and have them howling with laughter at the farting and poo references whilst reading between the lines and enjoying some of the more mature humour that will fly over the heads of youngsters.
Some of the details in the book are even educating, albeit in a probably useless manner except for general knowledge quizzes.
Sheer genius and a perfect Discworld tie in. Better that Where's my Cow, but not by much...