Like almost every well researched book that deals with the history of the holocaust this is upsetting and uncomfortable to read, but if you are interested in the subject I would say this is an essential text. It contains first hand accounts from interviews by the author of women who were prisoners and notably one of the women who was a guard. I don't recommend holocaust books, and I don't recommend the subject because the inhumanity on display is overwhelming to even the most thick skinned people. But I think it is on some level, necessary. I like Sarah Helm, I also read her biography of Vera Atkins, she is a diligent author, and her writing is clear.