Beyonce’s third solo record is a single album split over two CDs, to differentiate the two opposing sides of the singer’s personality — like the yin and the yang, the good and the evil or the fruit and the nut in a bar of Cadbury’s Fruit & Nut. This time around, it’s the fruit that takes the prize. The first half, subtitled I Am . . ., finds Beyonce veering out of her comfort zone into soft-rock ballad territory, while the second, Sasha Fierce, is a retread of the percussive dance sound of her last album, B’Day. Oddly enough, it’s the slower first disc — despite its profusion of Celine Dion-esque rhyming dictionary platitudes — that’s the more memorable half, thanks to a stronger set of songs like “Halo” and “Broken-Hearted Girl,” while Sasha Fierce stumbles tunelessly through a set of hyper-produced, rhythmic non-sequiturs. It’s fierce, but not exactly fun.