From the Spotify blog:

Every week millions of you lace up and hit the road to Spotify. Music is the perfect running companion but sometimes you need even more motivation to push on. That’s why Spotify Running is all about helping you go the extra mile.We’ve combined the best music on the planet – recommendations based on your listening history, multiple-genre playlists and original running compositions written by some of the world’s foremost DJs and composers – all tuned to your tempo and seamlessly transitioned to ensure you’ll never miss a beat. Start running and Spotify will detect your tempo, matching the perfect music in time to your step – making you a harder, better, faster, stronger runner.

This is Spotify’s latest move to distinguish itself from streaming competition from Apple, Pandora, Jay-Z’s Tidal, and the like.

The promo video is below. Pretty good idea.

I wonder if Spotify adjusts the feed as you speed up or slow down. I get the sense from the video that you set it up as you get started. If the tempo of the music is not reactive, not sure how useful this will be. Hills slow you down, terrain is inconsistent.

Seems to me, this is a perfect problem for the Apple Watch, assuming the Apple Watch is accurate enough.