I'm a little conflicted about this. The Echo Nest is amazing and does the kinds of things with music analysis that I can only dream of doing, so I wish them every success in the world.
But up until now they've been a fantastic independent force, not attaching themselves to any single music provider. You could use their APIs with Rdio, GrooveShark, whatever you felt like. I'm concerned that will no longer be the case.
Any company that has both the economic ability and incentive to acquire The Echo Nest would have the same potential to be one-sided in their acquisition as Spotify.
But up until now they've been a fantastic independent force, not attaching themselves to any single music provider. You could use their APIs with Rdio, GrooveShark, whatever you felt like. I'm concerned that will no longer be the case.