I have been wondering about these new services, too. It sounds like a great deal, but at the same time, I'm trying to save money and not have any more "bills" or "subscriptions" if I can help it. So, instead of paying a monthly fee, I keep using my external hard drives and the good old DVDs or CDr backup hard copies.
I know of a few other local people that own servers and charge a monthly or yearly fee for use. I know that is a great way to store or share whatever you want, and it is probably less than how much you'd pay for these other services.
Does anyone else have suggestions as to great ways to store/organize their cumbersome music libraries?