Does anyone on here use Strava?

If so, how do you like it? I've been looking stuff up online about it, but I thought I'd come on here to see if anyone has any input. :)

Edit: About Strava

Strava is a website and mobile app used to track athletic activity via GPS. For runners, this works really well -- there are a number of features available which include the ability to search the database for routes and athletes, complete in competitions/challenges, etc. Go to Strava.com to learn more.