This is above all a great novel, by a largely forgotten writer. While based on historical events, it is not intended as a history book. The reviewer who gave this one star because it 'has very little historical value' is missing the point. When he also says he 'couldnt manage to find any reliable source which proves and/or explain the so-called genocide' (sic) he is showing that he hasn't looked very hard. The Armenian genocide has been extensively studied and documented by professional historians. It was unanimously recognised as a genocide by the International Association of Genocide Scolars in 1997. It's not difficult to access information on it today - Wikipedia will start you off and point you to other sources.
Werfel's novels deserve a much wider audience - espcially The Forty Days of Musa Dagh, arguably his masterpiece. Werfel knew how to engage a reader, heart and mind, and had the intelligence and subtlety to portray a complex conflict with real insight. A magnificent achievement.