Had my Nike+ Sportband for about 6 weeks and used it lots. Never had a problem with it although I do find it measures distances differently from time to time. Not sure just how accurate it is (I use a pouch on my Brooks shoes) but it is ok as a guide to what I am doing. Only problem I have had is not being able to get it to calibrate a run despite having done specific short runs for this purpose - presumably it thinks I am running too slowly to not be classed as walking!