The reviews here seem to fall into 3 camps: the "it's a perfect masterpiece"" camp, the "he was duped by ODHA - 'who killed the bishop' got it right" camp, and the "he is a lefist fool" camp. I belong to none of these, so let me throw my two cents in here....
I spent a brief time in Guatemala doing human rights work in the mid 80's (a shout out to any PBI alums in the house :)), and so was interested in the subject matter, and had at least a glancing acquaintance with the horrid murderous travesty that was the Guatemalan government, as well as the impenetrable fog of denials, mis-statements, forgeries, violence, hidden agendas, disappearances and murk that hid virtually any attempt to get at any truth.
I found the first half of the book (which focuses on the "who-done-it") outstanding. Here Goldman relates the story of the investigation - the false leads, the disappearing witnesses, the hopelessly (and deliberately) contaminated crime scene, the (deliberately) conflicting evidence, the overlapping areas (and agendas) of the investigators, etc. That the investigators were able to finally pierce it (not completely, but most crimes never are) is just amazing, especially given the very real threat to themselves and their families.
I think the other reviewers who criticize this book for not analyzing the case for/against Monsenor Mario, or for not analyzing the case made by 'who killed the bishop' are being unfair - goldman spends a _lot_ of time on each of these, especially the latter, to the point that you could almost criticize the book for over-focusing on it. Similarly, I think criticizing the book for not telling more of the story of the defendants is ludicrous - when your primary interactions with a defendant consist of their giving you death threats, it's hard to go much further!
The problem with the book lies in the second half, what is called the "second crime" - the multi-year "war of attrition" against the verdict, year after year of judicial games, wars in the press, maneuver after maneuver. Here, while I appreciate the author's work in showing us just how deeply broken the justice system and press were (and are), I just felt the book became a less interesting read - we know who done it, we know why, now we read chapter after chapter of frustration (although it sure made me glad I've never been a guest of the Guatemalan Penal system!). One last cavil - another reviewer says that Goldman never walks us through the final 'best guess' of the final crime, minute by minute - oh yes he does, it's near the end.
So in summary - a good book, an important book, a book alternately deeply depressing and deeply inspiring, but not a great _read_, the only reason I am marking it down a little.