I think the splendour of 19-20th century Russia was portrayed well, with the parties and glamour so vivid and heavy in detail. It helped add intrigue to the plot, this world of royalty and riches with a hidden underworld of sorcery and darkness, all heralded by these two sisters of power. Although both points of view were portrayed the book focused more on Militza, the eldest, and her relentless ambition for power. Despite her sister wavering she carried on, and her ambition could also be seen as her hubris, as it propelled her down their precarious fall from the grace of the Russian royal family.
The book was however a little heavy on the history side, and I did get a little confused and lost interest in a few of the witchcraft/séance scenes. However it does deliver what you would want in a historical book like this: royalty, sorcery and secrets.