The young pianist Lang Lang is being extravagantly touted as the future of classical music. “Far from being intimidated by the pressure, Mr. Lang seems to be high on his success. But as on other recent occasions, his playing suggested that success is going to his head. When he first gained attention in the United States in 1999 at 17 he seemed an unformed but musically intuitive pianist with a white-hot, brilliant technique and an exuberant personality. On Friday, though, for all its color, flair and energy, his playing was often incoherent, self-indulgent and slam-bang crass.”