For a producer with endless platinum discs to his name and a peerless reputation for perfectly balancing commerciality with restless innovation, Tim "Timbaland" Mosley has always cut a strangely unfulfilled figure. Looking at his career, it's hard to avoid the impression that the startling hits he has essayed, for Aaliyah, Missy Elliot, Justin Timberlake and Jay-Z, among others, are scant recompense for his failure to become a successful rapper. It's not for want of trying - Shock Value is his fifth solo album - but the public who turn out in their millions to buy his productions elect to stay home when his name appears on the cover. His last single, 2004's Indian Flute, limped to a feeble No 73 in the US hip-hop chart. For all his genius behind a mixing desk, he's urban music's answer to Dennis Waterman in Little Britain, perpetually undone by his desire to sing the theme toon.
And yet, omens for Shock Value look good. Mosley has been on grand form recently, reinventing Nelly Furtado, helming the best bits of Justin Timberlake's FutureSex/LoveSounds, fearlessly wading into ever-more avant-garde waters with Bjork. On Shock Value, the supporting cast is more star-studded than ever: Timberlake and Furtado dutifully turn out alongside 50 Cent, Dr Dre, Elton John and Fall Out Boy. Single Give It To Me sensationally demonstrates Mosley's skills. It has one irresistible hook after another, but it also has moments of sheer unpredictablity. At its climax, Mosley suddenly brings the chorus in on the off-beat: the effect is jarring and exhilarating, as if the song has been turned on its head.
But it's not long before problems loom. Oh Timbaland wittily samples Nina Simone's Sinnerman, but the lyrics reveal one of Mosley's great flaws as a rapper. He has absolutely nothing to say, beyond reiterating the fact that he's a great producer in ever-more thick-necked ways: "I'm number one, you're number shit." Occasionally, he turns his attentions to the topic of sex with similarly demoralising results: "Let me see them big titties."
Curiously, his stellar guests also founder. Missy Elliot is on fine form, but, for some reason, Justin Timberlake is frequently required to adopt the persona of a menacing hard man. Alas, he doesn't make for a terribly convincing gangster, in much the same way that Phillip Schofield wouldn't make for a terribly convincing bare-knuckle boxer. More surprisingly, he gets into difficulties with the sexy stuff, although you suspect anyone would, given the quality of the material. "Bounce," he pants, "like your ass got the hiccups," a phrase that somehow seems more redolent of flatulence than wild sexual abandon. ("I got the remedy," he adds later, emerging from the bathroom brandishing the Wind-Eze.)
Dr Dre, meanwhile, seems to have caught a debilitating case of bad lyrics from everyone else. He attempts to lure "some young ho" by listing the many fruits of his riches. "I got a bungalow," he swaggers. A bungalow? What else you got, playa? A UPVC conservatory? A Wyevale Garden Centre account card? A Vauxhall Cavalier with a little tin of boiled sweets in the glove compartment? Sri Lankan rapper M.I.A.'s contribution is similarly disappointing, although her presence allows Mosley to demonstrate the legendary American grasp of world geography and foreign cultures, dazzling the "super Indian babe" with his knowledge of her native customs: "Girl, you and me need to go to your teepee." Perhaps when they get there they could smoke um heap big peace pipe.
The collaborations with rock bands sound promising - rock could certainly use an injection of Mosley's sonic futurism - but the results fall short of expectations. The Hives must have wondered if it was really worth the journey from Fagersta just to play the guitar riff from the Elastik Band's 60s garage rocker Spazz on Throw It On Me. Fall Out Boy fare better - One And Only adds a weirdly funky swing to their standard pop-punk thud - but Elton John is reduced to vamping some florid piano licks over a pallid beat, while Mosley mutters unconvincingly about what a work of genius the result is.
It's symbolic of what may be Shock Value's greatest failing. For all the trademark sonic trickery - honking rave synthesizers, fidgety beats, odd samples, vocal effects - there's a lack of decent songs. Occasionally, you get the sense Mosley knows what the problem is: at the end of a dreary ballad called Fantasy, he lingers lovingly on a chopped-up, heavily-effected vocal loop, as if even he knows it's the only interesting thing about the preceding four minutes. You leave Shock Value wondering if Mosley might not be a more pragmatic character than his dogged pursuit of a solo career suggests. Perhaps he saves the best stuff for his best-selling clients.