I can't see this system suiting many people
I watched the video when Steve Jobs introduced iCloud and thought it was all great and about time users had this facility...until he got to music. Maybe the system is fine if you bought all your tracks from iTunes or if iTunes has, and can recognise, your ripped CDs. But if there are items in your collection that don't match Apple's collection, the process is more of a kludge.
I watched Mr Jobs explain this kludge as simply and confidently as he could but I was not impressed or convinced. I thought, no way Jobsé.
For me, the disadvantages outweigh the advantages. But it's not the end of the world (that's 2012), if you don't like it, don't use it.