If you are interested in reading the memoir of someone who survived the reign of the Khmer Rouge, then I can't reccommend any other book higher. I have read two other books from survivors, but Ngor's book was by far my favourite.
What sets Ngor's book apart from the others that I have read is that Ngor was an adult when the Khmer Rouge took over. His memories are very lucid, and he fully comprehends what is going on around him. He watches his young wife die in his arms, those close to him betray, and everyone around him suffer. There are no high points throughout the entire odysey. Ngor brings you to the senseless and incomprehensible suffering that pervades every aspect of life under the Khmer Rouge.
One element I particularily enjoyed about Ngor's book is the extensive descriptions of Cambodian culture, attitudes and behaviour. Cambodian society (from what I can gather from what I have hitherto studied) is highly formal, with a rather complex series of formality set up for intereaction with others and a rather reserved character in regards to expression of feelings. The most important of which in this context being "kum," which is a sort of bitterness and longing for revenge, that becomes evident in a lot of what is happening. You will leave this read with a feeling of not only being inside of what is happening, but also for the actual mechanisms guiding behaviour.
This is, however, not a pleasant read in the least. The descriptions of the atrocities are beyond anything that I was expecting, and for that reason, I would seriously warn others that this is not for the faint at heart. Luckily, Ngor offers notes at the beginning of graphic chapters so that one can skip over them. You will lose sleep, and I can guarantee you that it makes any of those goofy horror movies like "Hostel" and "Turistas" look like a day at Disneyland. This horror is real, and not far in the past. Being that my normal area of study is Russian history, I have read a lot about the horrors of communism and tyranny, but nothing from the basements of Lyubyanka Prison or Mao Tse Tung's Cultural Revolution comes close to the abominable atrocities of Pol Pot's Cambodia.
Ngor also describes his role in the classic movie, The Killing Fields, as well as his integration of life in America. An afterword by friend Roger Warner ends the book on a particularily haunting and sad note, but rightfully so, none the less.
There are a lot of truely excellent books available by survivors of the Killing Fields, and this is the quintessential starting point for those who wish to learn more.