This is fantastic, but as someone who's playing around with making a music app, I'm still not really able to use it.

The unfortunate fact is if you don't have all the labels on board you're just going to irritate users- they have no idea who is on what label, and why should they?

That said, this is huge step forwards. Hopefully other labels will see the benefits and follow suit- it could make Echo Nest a huge player.