By Leah Greenblatt
Updated March 10, 2010 at 05:00 AM EST

Bieber Fever, ?the heady pop cultural delirium that seems ?to leave grown-ups untouched while sweeping every ?susceptible tween in its path, is now a ?full-blown epidemic — one characterized by shopping-mall riots, Twitpic raptures, ?and generalized episodes of mass swooning.

Its source, 16-year-old Justin Drew Bieber, has already racked up 150 million combined plays on MySpace and YouTube (and that’s not even counting the weepy-toddler video that recently went viral), a staggering figure by any measure. But the physical output of ?the Canadian export with the gleaming teeth, pinchable cheeks, and swoopy, insouciant locks of a ready-made pop idol has been ?limited so far to one seven-song EP, last November’s My World.

This full-length sequel, My World 2.0, in stores March 23, won’t likely affect any adults not in the direct blast radius of Bieber’s target range. That said, the kid seems to know what he’s doing: He drums and plays guitar, and he has co-writing credit on each of 2.0‘s 10 tracks, many of which cleverly update the sanitized R&B swagger ?of early-days Usher and Justin Timberlake. (Both, coincidentally, fought to sign him; Usher won.) Airy first single “Baby” has the sugar-high charm of mash notes and first kisses; ”Never Let You Go” sounds like a fraternal twin to Chris Brown’s ”Forever.” But the best by far is ”U Smile,” a shimmery slice of Hall & Oates-style blue-eyed soul. Bieber’s voice ?is still high, clear, and sweet; when it cracks, that may be a day of reckoning. But there’s real talent, it seems, under all that hair. B

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