sensor works quick and fast yet  doesnt turn on when hands are casually passing by farther away which avoids turning water on when you dont want it to.. you have to pass your hands within couple inches of sensor, which is a great improvement!!!!  
another faucet we had water would turn on when we didnt want it to ex: like pouring the meat juice into a pan in sink for gravy and faucet would turn on and water would pour... things like that