After owning 2 polar hrms, I opted for the Timex because of the ability to change the battery in the watch and the chest strap myself. My polar was out of warranty (M61) and about 7 years old. Most likely the cost of repair was nearly the price of a new watch. Anyways. So the timex. I've used it now about 4 times. I found the set-up somewhat clunky, first of all, and for it to track heart rate, the watch must be in "chrono" mode which i personally find unnecessary. I don't understand why this has to be the case. Furthermore, the calorie expenditure estimate seems quite exaggerated. Sure, i would like to believe i burned 553 calories in 51 minutes, but i was on the elliptical, so i doubt it. Unlike my polar, the Timex does not ask for sex or age, just weight, further decreasing the accuracy of the calorie estimate. There is often a discrepancy in the bpm between what the exercise machine says and what the watch says. Thus, in the case of this hrm, it is probably optimal for people who do not do their cardio on exercise machines with hr sensors. Thinking it would better deal with such interference was one of the reasons I purchased this digital model over an analog hrm. oh well. Also, I have to get used to the chest strap again, the 2 pieces, vs. the snapping polar model that was more user friendly. It is also less sensitive and sometimes take 10 minutes to get a reading. Despite my criticisms, I will most likely keep this hrm and deal with the issues. Maybe it is because i don't want to pay $[...] to ship it back? Perhaps over time I will like this watch better. Seeing my heart rate is motivating enough to keep me going, I suppose.