From the beginning, this book is unpleasant to read, so you have to force yourself to go on with it. On the other hand it is written in deceptively simple English, hardly any complicated vocabulary or structures.
The first person novel tells the story of an international drug-taking dropout society in Thailand. They neither care for the locals nor for each other. Their self-centred world is filled with the tasks of  getting dope, being stoned, playing violent computer games, finding a place “The Beach”, where all that is possible amidst a similarly minded community.
“Brave New World” by Aldous Huxley comes to mind, especially because the happy beach crew and the author don´t feel any ethical inhibitions. I suspect, though, that the events the author pretends to have really happened, have just sprung from his imagination, probably helped by dope and computer games, where he practises  fighting with his favourite Vietcongs.
I have to admit, that the story gives you food for troubling thoughts, long after you have finished reading. In this sense, it is an intensely moralistic book.