Encyclopedic is probably the best word for this book. It is laid out as a reference book, though readable enough for a dedicated (or obsessive) person to read cover-to-cover. Ryan's goal is to provide a survey of Russian magic for the non-Slavophone specialist, and he succeeds in his goal. Each chapter covers a different aspect of Russian magic (types of magicians, spells, amulets, etc.) from Kievan Rus' to the present. Ryan has divided each chapter into sections and sub-sections and makes frequent reference to other parts of the book, as the categories overlap considerably. The nature of the evidence, however, makes this a book mainly about the early modern period (when written evidence becomes abundant but before outside influences become near-overwhelming). In this course of his survey he tries with limited success to disentangle indigenous Russian beliefs from outside importatations; since Russia has never been culturally isolated, however, by the time written evidence becomes available for many beliefs and practices, there's no easy way to do this. The greatest influences were for many years the Byzantine Greeks, but Judaism and western Christianity strongly influenced certain areas, as did Turkic, Mongol, and other central Eurasian cultures, and pagan Scandinavian beliefs. He is able to find strong continuity into the twentieth century in many instances, and even a revival of some practices that had been repressed under the Soviets.
While the material is potentially interesting to the non-specialist, several editorial decisions have made this work more accessible to the specialist. Ryan frequently includes long lists terms in Russian, Ukranian, and other east Slavic languages(transliterated into the Roman alphabet where necessary). He also gives all Latin quotations in the original, usually without translation (though Russian is usually translated); likewise short phrases in Greek (again, transliterated, though longer passages are generally given in translation).
Documentation is thorough, and Ryan has been at pains to consider current and older scholarship and give detailed summaries of unpublished primary source texts. He also often points out scholarly debate on various issues, though there is undoubtedly more debate than he was able to summarize, even in such a substantial tome as this.
Overall, this is a worthwhile work for a specialist wanting a single-volume reference work, and will potentially find favor with those amateurs who are not easily put off by the languages required or technical terms.