Here is npm's response: http://blog.npmjs.org/post/151660845210/hello-yarn
That's insane. It wouldn't surprise me if yarn becomes popular and its proxy to npm slowly turns off and boom, everyone would be migrated and npm would be left with little to no users. Yeah that's probably unlikely for the immediate future but Yarn is positioned perfectly to siphon off npm's users very painlessly.
http://blog.npmjs.org/post/78165272245/more-help-with-selfsi...
I think it's a great example of moving a little too quickly, honestly. Especially since it bricked plenty of npm installs instead of being "just another bug".
I love the service they offer. Not a fan of the tools or pace. Npm comes in the node installer so why do they even have to care about improving?
Just my thoughts.