Not worth the price – Kello Review

In a nutshell, it doesn't work. Most of the time the mic isn't sensitive enough to pick up a stable sound signal. When it does (loud watch and very quiet environment), the measured rate is all over the map. My watches are generally within a couple of seconds of correct time, but you'd never guess that from looking at the readings from Kello, which suggest that they're varying by +- 20 seconds. Needless to say the results don't match the output from a timeographer.
Review by Forum seeker on Kello.