An unprecedented album-length collaboration between rap and R&B superstars, The Best Of Both Worlds unites the sensibilities of Jay-Z and R. Kelly, two acts who share more than just healthy bank accounts and mammoth legal bills. As the self-appointed "God MC" and "R&B Messiah," respectively, they each possess a more-than-healthy sense of their own artistic worth, as well as a knack for crafting hit songs while maintaining street credibility. But while R. Kelly and Jay-Z are the primary forces behind Both Worlds, the album also boasts a far-less-promising voice in the form of the schlock-friendly production team The Trackmasters. Why two huge stars would hire the team that jacked the chorus for "Everybody Wants To Rule The World" for a recent Nas track is open to debate, but The Trackmasters' presence on nearly every song undermines Kelly and Jay-Z's lofty ambitions. In a trademark act of bravado, Jay-Z begins Both Worlds by comparing himself and Kelly to Martin Luther King and Malcolm X, opening the album on a somber note. But it soon takes a detour into the more chart- and club-friendly realm of R&B-inflected pop-rap. On "Green Light," Jay-Z admonishes listeners to be as pimpish as they want to be, but he and Kelly need no such permission to flaunt their superstar lifestyles, sexual prowess and appetites, and brand-name fetishism. The Trackmasters' production, unsurprisingly, aims more for guilty-pleasure pop than the soulful timelessness of Jay-Z's The Blueprint, but on tracks like the Lil' Kim-powered "Body," it's easy to get caught up in the pair's materialistic dream-world of unlimited sex, money, and power. On his third album of the past year, Jay-Z sounds frisky, goofy, and defiantly casual, although he's overshadowed yet again by a Southern cult star on "Pussy," a showcase for the laconic lyrical prowess of Devin The Dude. R. Kelly doesn't fare nearly as well: If Both Worlds were a fight, Jay-Z would win in a knockout, while Both Worlds "referee" Tone of The Trackmasters would be fired for his competent but generic R&B wankery. The humor in Kelly's music has often been unintentional, and that's certainly the case with his sole solo showcase, "Naked," a ripe love-jam in which he promises to stroll through a lovely lady's "garden of love" during a night of clothing-optional delight. As a fun, disposable pop album, Both Worlds seems tailor-made as a soundtrack for spring-and-summertime decadence, although the hackwork of Kelly and The Trackmasters keeps it from living up to its title.