Comebacks are almost as tough to pull off as consistency.For his first full-length album in almost a decade, pop superstar Justin Timberlake aims to reassert his firm grasp on the zeitgeist, last felt in the wake of 2006's FutureSex/LoveSounds.That record, with its icy synths and smart embrace of the then-burgeoning dance music genre, sold more than 10 million copies and won a handful of Grammys.Its hotly anticipated follow-up and Timberlake's third solo effort overall, The 20/20 Experience, is more frustrating, and honestly, part of that may stem from unreasonable expectations stoked by Timberlake's pop culture carpet bombing runs in the lead-up to the album's release. Dude's been everywhere, from the Grammys to Saturday Night Live to South by Southwest, to remind folks that his stint in Hollywood is over and he's back to making music.What Timberlake, who once again teams with producer Timbaland, could not have anticipated is just how radically different the pop music landscape he returned to would be. What sounded ahead of the curve in 2006 did, in fact, become the template for a while, but Timberlake's time out of the game has allowed other artists like Frank Ocean, Bruno Mars and Mayer Hawthorne to eclipse him and, in the process, bring revivalist soul and future-shock R&B to the fore.And that's what is most surprising about these 70 minutes (multiple tracks cruise past the five-minute mark): Timberlake sounds, well, like just about everyone else on the radio.Sure, he's still got an immaculate instrument -- his falsetto gets a healthy workout during lead single Suit & Tie -- and a knack for letting the beats breathe, but far too much of The 20/20 Experience sags when it should soar. Only one cut, the anthemic Mirrors, could genuinely be called compelling. More often, there's nothing beyond a refrain to grab hold of: Let the Groove Get In consists purely of that phrase, repeated for more than seven minutes.Songs built around smart imagery (such as Strawberry Bubblegum) or fascinating sonic compositions (atmospheric album closer Blue Ocean Floor) are undone by excessive length. Timberlake doesn't need to appear in umpteen ads or saturate the media -- he needs an editor to help trim the fat and make the product more compelling.Reports surfaced this week that a second installment of The 20/20 Experience is due this fall, and likely, the hype surrounding part two will be less intense. Having handled the comeback part of his music career, Justin Timberlake (and his audience) would be well served to focus on consistency.