I have read and seen the movie some 40+ years ago.The book was intersting especially for Indian guys like because there was a powerful wave of Communism that was gripping the states like Kerala,West Bengal etc..India too was a recipient of American aid,some PL something which was mainly milk powder ,blankets etc..and the Communiste were strongly protesting against that aid.
Looking back,America eventually could little endear themselves with ordinary Asians then where as today they are liked and welcomed in much of Asia.America's continuus help to rebuild Vietnam today seems to pay off and we can see the Vienamese warmly receiving the American tourists and officilas.
The Ugly American helped ordinary Americans understand how their consulates and officers were functioning then and its failures.