On his 2002 solo debut, Justin Timberlake was so delighted with his own audacity he could make jaws drop just by saying “good morning” to the ladies. On his skilled but sometimes labored follow-up, however, the liberated ‘NSync frontman bears the weight of experience that drags down so many maturing lovermen. No longer an innocent on the cusp, he knows more about sex than you do, and when he talks about whips he doesn’t mean cars. Why this or anything else qualifies Justin in particular — rather than Usher, say, or new confederate Will.i.am — to “bring sexy back,” as the follow-up’s Timbaland-produced lead single boasts, isn’t altogether clear. Although his best new tracks are thrilling — even the smashing “SexyBack” is trumped by the classic-Timbaland “My Love,” where bells introduce what will become an abstractly twisty beat and a T.I. cameo is only a fillip — some of the up-tempo stuff flirts with mechanical muscle-flexing. Except for the Rick Rubin-produced finale, “(Another Song) All Over Again,” the ballads could make you wish the “love sounds” of the title were gasps and squeals. And the well-meaning anti-crack song is a clueless embarrassment.