I'm intrigued, mainly for the remote backup functionality. My main concern is bandwidth and data usage. I have satellite internet (no choice where I live; too remote even for cellular), which means I have a data cap of 25GB a month up/down. Uploading all 400GB of my library would be impossible; even if I could get it all uploaded, the mere act of listening would quickly use up my data allotment.
But the idea still interests me... if I ever move to a place with unlimited DSL or cable internet, I might take the plunge.
One thing that I don't get. If I have a copy of "John Tesh Live at Redrocks", and my friend Skippy does too, why do we both need to upload it? Can't the system somehow recognize our files and see that we both have complete, legit versions, and just let us both access one file? Yeah, this would mean a large database of indexes; but surely that's less processor and HD intensive than making all 5,000,000* owners of this masterpiece upload it on their own?
*this figure might not be factually accurate... ;-)