Until the exit for Verizon branded iPhone 4, Apple has always chosen for their melafonini a vibration of classic: a small rotor is mounted a counter that, with the movement, producing shake the device. The main problem of this solution is to be noisy and a bit 'spartan, with the production of sounds not properly pleasing and the displacement of the smartphone evident when resting on smooth surfaces.
With the Verizon iPhone 4 and iPhone 4S, Apple has instead preferred a linear oscillator more quiet and discreet, can achieve the same effect without alerting the owner, however, be a victim of the faults listed above. Something, however, did reverse the trend of Cupertino: iPhone 5 has returned to the rotor counterweight., Thereby restoring the old component and the old sensations. It can not have been the right choice, because otherwise explain the step back taken by the engineers in Cupertino.