In addition to being a delight to read, it's an important work of forty year's worth of insight and observation on 110 of the most interesting people that have shaped our shared Culture. Not just America, but worldwide.
At times, novelistic, at others academic, and even others, wholly unpredictable and surprising, the book offers unique insight into towering intellects, audacious egos, and simple savants, who at their core are all very human indeed.
It's as much brain candy, as reference guide. Go get a copy. If not - enjoy the series that Slate is providing on line.