Be honest with yourself: the only reason you log into Runtastic with a Facebook account is so that you can show everyone else how much exercise you're doing. Now you can show off in a more direct way with Leaderboards. This is basically a mobile version of the leaderboard feature that was recently introduced on Runtastic's web service, which tracks total miles or kilometers covered by you and your Facebook, Google+, or Runtastic contacts who use the app.
If you're looking to beef up that list, version 6.0 also lets you add friends directly from the app itself - just tap the profile outline in the top-right corner. Other new features include a new Story Run, The Tetradome Run III ($1 in-app purchase required), and Runtastic has added "Real Voice Coach." The app has had a vocal coach feature for years, but according to the changelog on the Play Store it's been improved: "Enjoy our new Real Voice Coach for an improved performance & personal trainer-like encouragement."