Keen's relentless "polemic" is on target about how a sea of amateur content threatens to swamp the most vital information and how blogs often reinforce one's own views rather than expand horizons. But his jeremiad about the death of "our cultural standards and moral values" heads swiftly downhill. Keen became somewhat notorious for a 2006 Weekly Standard essay equating Web 2.0 with Marxism; like Karl Marx, he offers a convincing overall critique but runs into trouble with the details. Readers will nod in recognition at Keen's general arguments—sure, the Web is full of "user-generated nonsense"!—but many will frown at his specific examples, which pretty uniformly miss the point. It's simply not a given, as Keen assumes, that Britannica is superior to Wikipedia, or that record-store clerks offer sounder advice than online friends with similar musical tastes, or that YouTube contains only "one or two blogs or songs or videos with real value." And Keen's fears that genuine talent will go unnourished are overstated: writers penned novels before there were publishers and copyright law; bands recorded songs before they had major-label deals. In its last third, the book runs off the rails completely, blaming Web 2.0 for online poker, child pornography, identity theft and betraying "Judeo-Christian ethics." (June)