You're giving this book three stars because it covers a "hateful and tragic period in detail"? Did you think a book which talks about Cambodia and the Khmer Rouge was going to be the next Mary Poppins? The fact that the author was involved in "The Killing Fields" might have been a subtle clue that this would be dealing with a terrible part of human history. You can't mark the book and the author down for going into detail - that's the whole point! I'm sure the author would have loved to have been writing about funfairs and parties and chasing bunny rabbits across the fields but unfortunately fate didn't give him that oppportunity. Should books on the Holocaust tone down the details a bit because they are unpleasant? On the contrary they should shock us and be "heavy going" so that these things are never repeated again. And we also deserve to get the full truth. The last thing you want from a book about the Khmer Rouge is to say, "Well they weren't so bad". But it appears that this is what you would have preferred!
Needless to say I think your review and especially your rating are seriously flawed and should be amended. Hopefully you will see the sense in doing so.