Thailand is infamous for being a sexual shangri-la for Western men, a place where even a dopey-looking Brit (like the guy in this movie) can be a "butterfly man", flitting from one pretty Thai girl to another. Nevertheless, this movie seems VERY romanticized. In fact, it borrows heavily from one of the most romantic love stories of all times, "A Farewell to Arms", even though the Far East "sex tourist" trade hardly provides the dramaticic background of the World War I setting of the famous Hemingway novel.
I've only spent a short time in Thailand myself, but nevertheless several things in this movie struck me as inaccurate or at least very highly romanticized. The Thai prostitutes may be more demure than other prostitutes, but they're probably no more likely to have the mythical "heart of gold" like the girl in this movie does. I also found it a little too convenient, given today's political climate, that the girl's vicious pimp is an American. American soldiers may have heavily subsidized the Thai sex trade during the Vietnam War, but it probably owes a lot more today to the Europeans, the Aussies, and the Japanese. And Americans certainly are not running things (the guys who were always trying to drag me off the Bangkok streets and into the go-go bars and massage parlors all pretty much seemed to be locals).
This movie is lyrical and heart-breaking like other reviewers have said, but it is also somewhat at odds with a reality that is often just seedy and depressing. See it by all means, but balance it out with something like "Lilya 4ever" which is equally lyrical and heart-breaking but also much more realistic.