I have seen this book hailed far and wide since it first appeared in 1995, and having just read the latest edition (Carroll & Graf/Robinson Publishing, 2002), I must side with those who call this the best book on the subject. Sugden has examined all of the available primary materials himself, uncovering some material that had hitherto been overlooked. As a result, his analysis of possible suspects, the number of murders that can be reasonably claimed for "Jack", and the reliability of several oft-quoted documents (including the contemporary letters to the police and the newspapers) are remarkably level-headed, his interpretation free of the kind of special-pleading and preconceptions that have marred so many other studies.
When approaching common myths or misconceptions, he carefully compares the small amount of (frequently misquoted) evidence that gave rise to them against the phalanx of evidence that proves them to be untrue or unlikely.
He also tells us as much about all of the persons involved - suspects, investigators, witnesses, and victims - as we could reasonably expect, and this quite frequently adds an element of pathos or irony to events that we were denied (or had come to mistrust) in other sources. This has the happy result of making many of the participants in these events take on the contours of real people rather than the paper cutouts from old pantomimes we have been offered all too often in the past.
If a witness offered a different version of events in different interviews or later memoirs, Sugden offers the various versions, places them into context (why do the details vary and are they significant?), and then weighs the reliability of this witness's testimony as a whole, based on witness-reliability studies that have been available to psychologists, sociologists, and criminologists for decades. Refreshingly, he neither sensationalizes nor sentimentalizes, which means that his analysis of the Eddowes case, to cite one example, is the most thorough and most moving account I have read. None of the gruesome details are glossed over, thanks to Sugden's strict adherence to witness and pathologist's reports. All the sad ironies of Eddowes' appearance at this particular location, practically against all odds, are also underlined by a careful examination of police reports and accounts from her friends and family. The accumulation of detail has a relentless quality to it which gains more power from Sugden's clean and unmannered prose that it would from melodramatic underlining or sentiment.
Short of a more fully illustrated version of this same book appearing in hardcover at a later date, I cannot imagine a better book on the subject.