A book that is beautifully written, but that has to undergo historical scrutiny. Since it is mostly a memoir, written from the standpoint of Yugoslav dissident Milovan Đilas, no effort has been made into incorporating or listing sources (which is, given the style of the book, understandable). Moreover, the somewhat frustrated and salty reflection on Yugoslavia as a political project tends to far outweigh positive reflections, which are usually little side-notes in a barrage of criticism. I do not blame the writer for this, however, given his personal history.
There are a few reasons why I do not deem the book entirely trustworthy as a historical document:
1) A lack of sources and references that support the key-points Đilas attempts to make. Any claims that he makes would have to be researched extensively and thoroughly. After reading the book and having limited knowledge about Yugoslav history, I cannot really state for certain whether some of the claims are true, false, fabricated, verified at a later time, etc.
2) Dissidents are an important phenomenon in political history, but their statements are difficult to isolate from the fact that dissidents are usually highly in demand on the side of their government's opponents. This creates an incentive to pander to a certain audience, especially if writing or political commentary is your main profession. Yeonmi Park, a DPRK-dissident, is a well-known example of a dissident who is able to give an exclusive view into DPRK-society, but has been known to also utter incorrect statements. In my opinion, works of dissidents have an even more significant burden to provide sources and references, since writing about socialist countries and societies (and the leaders who govern them) is too often grandly sensationalised.
I believe that the main-pull of this book, regardless of historio-epistemological issues, is Milovan Đilas' perspective on Tito as a personality, as somebody who spent a better time of his formative years with him. Đilas provides interesting insights into how Tito could be perceived as a person, how he (allegedly) acted, etc.
I recommend reading this book, although with a grain of salt and with an appropriate critical attitude.