To start with, the instructions in the app do not cover all of the functions of the watch so something as simple as resetting the stopwatch so you have to go by trial and error. Worse, the heart rate monitor simply doesn't work. Half the time, it says to "adjust the strap", usually when there is any sweat under it which is...you guessed it...exactly when you want a heart rate monitor! When it does work, it is barely useful because the readings either are totally inaccurate or lag by so much as to not be useful. Customer service is useless (reset...reset again...reset again again again...that didn't work? too bad).