I love the fact that you can signup for a ZuneMarketplace subscription. I have very open-minded music tastes and I love to listen to all types of music. The Zune subscription allows me to listen to just about anything I'd ever want to hear. I was a subscriber of Rhapsody (ToGo subscription was $15/mo, same as Zune), but now that I have a Zune....

As far a library music, I'm a mobile DJ. I have over 400 compilation CDs (about 16-20 tracks each) and about another 450 artist/group albums--though soon to be re-burned to compliation (less fluff to carry in my cases.)
I'd have to agree with Tai, I like having CDs. Although some of my CDs are so old that they're starting to degrade

Time to re-rip and burn before they're lost!