From Engadget’s in-depth Zune HD review:
Perhaps the most compelling reason to buy a Zune HD right now isn’t the gorgeous screen or forthcoming apps, HD radio, or slick design. Make no mistake about it – this is a fine, fine device, and no one would fault you for buying one – but it’s not the device itself that is the most attractive part of this package. To us, it seems like the single most compelling reason to choose this device over something like the iPod touch can be boiled down to one thing: Zune Pass.
I’m not sold on subscription music, but I know a lot of people who love it.