The watch fails to accurately track distance or time /- 10-20 percent. It failed to accurately award the Heart challenge. The watch activity tracking is useless without carrying your iphone since the time and distance are even farther off.

These adjustments work initially to resolve the inaccuracies. Over a few days it again fails to track accurately. I walk the same route every day usually at somewhere near the same pace. I use the watch every day three or four times a day and depend on it for monitoring my exercise activity. The failings are frustrating.

I am suspicious an algorithm adjusts what is considered to be a 'brisk walk' according to data it collects. So if I feel really good and walk faster, it ups the definition of a 'brisk walk' and that affects the results on subsequent workouts. You need to add an option to allow users to disable the 'brisk walk' functionality or to enable it if desired. I can carry the phone to help make the watch work right but that should not be necessary. Nor should I have to constantly readjust the data to make it work.

I have physical issues which make it important for me to know how far and how long I walk in exercise sessions. Your "logic" defeats my ability to do that and makes the watch less useful to an entire group of users who have similar needs.. While you may believe your scientific definition of a 'brisk walk' fits everyone, you would be incorrect. Please fix this issue.