In my strange Wiki-knowledge I think I remember that it is his first big seller, the book that established him as a public figure. Since it sounds plausible, I'll go with that.
Essentially its a story of what is now called "ugly Americans," but it is funny enough that one might forgive them. Here is an example:
We are camped near Temnin-el-Foka -- a name which the boys have simplified a good deal, for the sake of convenience in spelling. They call it Jacksonville. It sounds a little strangely, here in the Valley of Lebanon, but it has the merit of being easier to remember than the Arabic name.
When I read it yesterday, I snorted a little, out loud, on the train. Admittedly, I was tired and my defenses were down, but I still contend that the book as a whole is very amusing. And even, at times, informative.