Been a distance runner for over eight years and tried out the Nike+ for about a month two years ago. Basically it's not accurate. Mine was off on pace and distance constantly. It's in the garbage now.<p>The way I calibrated it was I ran on a treadmill at a constant pace for 1 mile. After I'd get pace results that were off by a minute sometimes, and mileage results off by 1/10th of a mile. I calibrated it like 20 times before giving up on it.<p>That might not seem a lot, but to a serious runner it is. A 6:00/mile pace is far more grueling than a 6:30/mile pace. I ran a 1/2 marathon with it and Lance Armstrong congratulated me for finishing when passing the 11.5 mile marker. Uh, another 1.6 to go dude. If I let it pace me it would have ruined the race for me. Fortunately stop-watches and mile-markers still rule all.<p>You can look at reviews for it on Amazon. Many had the same experience I did. People still buy them though because people like stats. "You finished a marathon. Achievement unlocked!" etc...<p>It's more for new/amateur runners to the sport. They don't care so much about accurate pace and distance. Just having something say "You did good!" makes them happy. Running for 30 minutes is difficult enough for many, without worrying about accurate stats. And heck, if that gets you running, by golly go and buy one! The more people taking care of their bodies the better! :)<p>--------------------<p>The idea behind the uploading of your workout data online is really cool though. If it was replaced with a GPS unit, and the cost stayed affordable, lots of problems solved for runners like me. Garmin has a nice, albeit bulky, runners GPS wrist-watch unit, for $300...<p>--------------------<p>The data saying "5 uploads and you're hooked" probably has a lot of more "serious" athletes like me dropping out before hitting the 5-upload mark.