Syncing all devices is fundamentally wrong and broken. Apple won't get it right until they drop the concept.

Try controlling what music from your vast library is currently on your tiny iphone. It's a god damned nightmare. Apple wants to "sync" which is just the wrong paradigm.

My phone is not synced with my itunes library. It's just contains a very small subset of it. If I were to draw a Venn diagram of "all the things" it would contain my iphone5, iphone4, ipad3, macbook, other icloud data, plus data on Apple's servers about what apps and TV shows I own but currently do not exist on any device in my possession. Each circle in the diagram has varying degrees of overlap with all the other circles. Not a single one is fully contained in any other. To proclaim that all of these devices are "fully synced" is just plain wrong.