I can't stop playing with my new Zune 8. It's lovely to look at and hold, the UI is great, and the sound is super. I had no complaints with my iRiver Clix, but since Urge, the subscription music service I was using, merged with Rhapsody, I had to find a new music player (I would like to avoid give Real any money ever.) Contrary to what Steve Jobs asserted, some people (including me) really prefer all-you-can eat subscription music over purchasing songs $.99 at a time.
The only real complaints I have are around accessories. I couldn't find any cases or armbands for the Zune, which I need before I can use it running (I dropped by Clix several times, so I know I need some kind of protection for the Zune). Also, my car has an iPod adapter; as far as I know, there isn't a Zune-to-iPod convertor, so I may be out of luck there. I'm sure at least the case/armband issue will resolve itself in a few weeks, but I'm a bit stuck on the car thing.
I'm a pretty tough critic of the work we do at Microsoft; as cool as some of our stuff is, we can definitely do better. However, once in a while, we do something very slick. The new Zune is one of those times.