The Plantation Act gives us an excellent opportunity to hear Jolson's voice as it sounded during his prolific Broadway run. And to judge, even by this 1925 recording, his voice is astonishing. It is rich, complex, and very, very powerful. Pay particular attention to the end of "April Showers." Jolson performs some amazing vocal pyrotechnics, impossible for any other pop singer I've ever heard, a long note on the word, "come," he actually changes the timbre of his voice in a way I have not heard from any other singer. It is truly remarkable.
One does get the sense that Jolson is particularly uncomfortable in front of the camera (as he would be for the remainder of his career). He seems to want to break out and bound around the stage, as he would have in a real show. It is nevertheless worth hearing just for his voice.