Continental upper class males with little to do, usually eat, drink and philander. Anglo-Saxon upper classes frequently engage in literary endeavors. Simon Sebag Montefiore is a graphomaniac of distinction. "The World" is a 1200+ pages compilation similar in scope and concept to the Will and Ariel Durant "Story of Civilization", only with a lot of sexual details unmentionable in the 1930s when they began their magnum opus.
The book is a wonderful reading during insomnia but, otherwise, is a non-insightful compilation of facts, part correct, part erroneous, largely in a chronological order. Simon Sebag is not shy mentioning illustrious Montefiores of the past. I (and hardly anybody else) can verify all the stories in this enormous volume and, more importantly, their sources. So I mention only the errors from the Soviet history, which come to mind. Maybe, historians of antiquity, middle ages and the like can walk through his narrative in their field of studies. But the concentration of the factual errors in one small section sheds an untoward light with respect to whole endeavor.
The information that Leonid Brezhnev was instrumental in arresting Lavrentii Beria appears exclusively in the fake memoirs of Pavel Sudoplatov, Stalin's chief of assassinations and is not credible at all. Brezhnev also was not a prime mover of the conspiracy to remove Nikita Khrushchev but emerged in the end as a compromise candidate between the coalitions of the "old guard" (Ignatov, Voronov, Podgorny) and the "Young Turks" (Shelepin, Mazurov, Semichastnii). So he belonged to the clique of the fence-sitters (himself, Andropov -- then the Secretary in charge of the relations with the Eastern Block and Suslov -- the chief ideologue) who procrastinated until the outcome of the impending coup became clear.
The power coalitions considered his appointment an interregnum similar to the Malenkov and Bulganin tenures in mid-fifties, before Khrushchev consolidated his power. However, the co-conspirators severely underestimated Brezhnev's acumen and cunning and were removed one by one, the latest -- Nicolai Podgorny -- the nominal head of the Soviet State, in 1977, a dozen years since the coup.
The closer he moves to the Russian present, the least credible are his sources and more-of-the-cuff are his conclusions. This would not annihilate the whole volume if I were not suspicious that a similar number of factual errors and gross misjudgements are not present in, for instance, Arab or Persian sections of the book.