I just bought this as a X-mas present for my mother who is a French-English interpreter/translator, and read it during the train ride back home. I ended up having to close the book because it was so damn funny that I laughed out a bit too loud, which seemed to upset the other travellers!
A very useful book that uses humour to make it's point. The expression is written in French, than translated literally in a Blake and Mortimer extract (thats the very funny part), and next to it is the correct translation of the expression in English. You flip the book around and it's the same thing, only English to French.
It does not matter that you are familiar or not with the Blake and Mortimer comics, it's funny either way.