John Gregory Dunne's [Vegas] is as good as it is difficult to classify. I've been trying to put a label of some sort on it ever since I finished it. He subtitles it "A Memoir of a Dark Season," and that sounds like just another arty, slightly cryptic subtitle, but in this case it is justified; the author is being helpful—and precise. Dunne has a reputation as a "new journalist" left over from a time when the phrase seemed to mean something to people. The book's subjective tone and tight, strong dialogue make it look like a novel, sound like "new journalism." Well, it's not—not, in Tom Wolfe's sense. No, Vegas is far more personal than that. John Gregory Dunne, in fact, has been about as frankly personal about himself as anyone ever has been in a book—and so the subtitle, a caveat lector discreetly...