I know a lot of people who've been in two minds over whether the paying version of Strava is worth it. Until recently I would've said no, but they've really innovated it in 2013 and it now boasts quite an array of features (see here http://www.andbethere.com/2013/02/so-is-strava-premium-worth-it.html). Particularly for riders with power-meters, there seems to be a lot of new analysis options on the site, with more coming later this year. Another factor to bear in mind is that they now have the raceshape founder on board. So many of those external features people used for segment analysis should now be integrated! Let me know what you think