Frank Ocean is a great artist, but not a particularly gifted vocalist, at least not in the traditional sense. His range is rather limited, his phrasing is straightforward and voice is somewhat generic. His power lies in the risks he takes, as a musician, songwriter, and as a personality. There are few albums of the past decade as adventurous as Channel Orange, and there have been few celebrities who’ve navigated the media machine as seamlessly and eloquently as Ocean. Stripped of the context of his own music, his guest turns work best when he’s allowed to be himself; either in the prickly politics of “Church in the Wild” or on the laconic, SoCal anthem “Sunday.”