To answer a question above, the reason to read this is because people like Timothy Snyder (one of the more celebrated historians of today) uses it in his courses. Of course, he’s not the only historian to do this. The meticulous research, using the sources available from Soviet archives, as well as many, many other sources, is evident in her work. While not an historian, she is a Pulitzer Prize winning journalist with political, diplomatic and journalistic contacts throughout the world. Her works are detailed and informative.
While the above is no reason, whatsoever, to not read Zemskov’s work (everyone should get multiple legitimate sources) and judge each text on its merits and not dismiss something simply because we disagree with it or because of the source. After all, we should play the ball, not the man.
I recommend this text because of the research, the considered interpretations and the easy writing style. While not THE most detailed work I’ve read on the subject, it’s far from the least