There are, of course, many films where the music doesn't matter a damn, where one doesn't even notice it. It's not so much that these films' directors were negligent, but that they lacked interest--they were not musical. But Tykwer (like Charlie Chaplin and John Carpenter, who also composed scores for their movies) is musical, to such an extent that he calls the opening track for Run Lola Run "Believe," the very "essence of the film," which implies that, for him, music is the point from which he elaborates, the point from which he constructs a film.
Admittedly, the thumping techno he composed to complement, worship, and enhance his electric darling (who also contributes hypnotically sensual vocals to some songs on the soundtrack), is not the best techno in the world; in fact, on the CD it sounds a little weak. (Wisely, Twyker has enlisted professional techno heads Operation Phoenix, Clemek, and Sun Electric to remix and improve some tracks on the CD.) Nevertheless, the music is perfect for his perfect little film.