The Nike+ application is infuriatingly defective. A sensor is purchased for $20.00 to be placed in special shoes that cost over $100.00. This sensor then communciates to your iphone providing workout data such as pace, distance and time. The application is notoriously defective however, in that often the sensor does not communicate effectively, thus causing incomplete and inaccurate data to be stored. For example, the application often will keep track of workout time, but will not measure distance or pace, thus reducing your iphone to a very... read full review »