The real world application varies upon the application and the type of the signal. If linearity is not a concern, then the above circuit diagram can be improved to remove the 47(ohm) resistor and the circuit will act as a digital circuit, with almost no sound when there is no light.
On the other hand if linearity is a concern for analog applications, then the above is suitable to provide analog output specially if the amplitude of the light is to be varied on both sides of the normal value (i.e. if the value changes both above and below the dc value). Just check up non-inverting transistor amplifiers for more information for the circuit.
A lot depends upon resistor values of the CDS cell and the resistance of the headphones. Moreover, you might want to connect a capacitor between the output and the headphone to dc couple the output.