Useless is bit extreme criticism. I'm not an athlete or super intense, but somewhat more active than average (regular strength training, hiking 10-20 miles 3000-6000ft gain, bike ride 25-35 miles). It works just fine, its precise enough -- and I don't care about extreme precision. Sure there are better devices out, and battery will last much longer for bigger hikes, but its good all-around for most people which works for both active and regular life.