I think it's great that amazon is doing this. Screw the big labels - this is still a person listening to music that they bought or whatever.
With that being said, I don't care about cloud storage or uploading songs to a little cloud drive. I'll just bring mp3s to work like I always have.
I know cloud storage has great potential for things like storing really important documents or offsite backup or whatever, but internet connections are just too slow for most of that to work for me.