The cloud would be great if it wasn't so fragmented. Xbox cloud services don't work on mac, iCloud doesn't support Windows Phone. Amazon cloud, google cloud.. there are just too many of them. If I didn't have to manage 50 million cloud accounts, I would understand its purpose.
Now, you are forced to buy into a specific ecosystem (iDevices, Google, Microsoft, Amazon).
The thing that I worry about is "ownership." If I buy a movie from one service (iTunes for example), it is linked to my apple ID. I become locked into the deals that Apple makes with Movie studios. I can't just sell my movie to a friend if I don't want it anymore. I can only watch it on iDevices. I can't get most movies in HD on a PC when they are available on the iPad and AppleTV.
If I end up wanting to switch to a Microsoft Ecosystem (Zune, Windows Phone, Xbox), I will have to buy all of my stuff all over again.
You end up paying the same price for these goods, but you lose a lot of "ownership."
My ideal cloud would allow me to share files cross platform, sync contacts and calendars across ANY device, and ultimately let me do what I want with the items I own. Of course, this will never happen because of the fierce competition across tech companies today.