A friend gave me a Garmin for Christmas last year, and ever since I've had it with me whenever I take a bike, which is always, and I log almost every mile. I've become an obsessive mileage counter, for no good reason, as I'm not training for anything, and I don't win a prize, but it adds to the fun. I use it even when I ride bike share. I used a cell phone for a while before I got the Garmin, and it was more hassle, and less accurate. GPS can do wacky things in urban canyons; the Garmin came with a speed sensor. I don't use Strava, I don't care about segments or KOMs or beating anyone's time, but I use ridewithgps.com to track things.