If an electrolytic potential is applied to the solution through a working electrode, then the measured current depends (in part) on the concentration of the analyte.
More of the analyte will slowly diffuse into the volume of solution close to the working electrode, restoring the concentration.
The chief advantage over direct amperometry is that the magnitude of the measured current is of interest only as an indicator.
Thus, factors that are of critical importance to quantitative amperometry, such as the surface area of the working electrode, completely disappear from amperometric titrations.
The chief advantage over other types of titration is the selectivity offered by the electrode potential, as well as by the choice of titrant.