I personally really like the zune. The interface is really nice, and the controls work really well. I am probably the only person who hates the click wheel and touch sensetive interfaces like that. I like to feel the clicks, so I know how many times I move the curser or whatever. I like being able to work the player through my pants pocket, without needing to take it out. I am also liking the idea of the subscription service. If it's got enough of the music I like I probably will subscribe to it.
It does look a considerable amount bigger than the ipod, though I am coming from an iriver h320, so anything is smaller than that thing. Size isn't a huge issue for me, as long as it fits in my pocket.
The only things I'm waiting for before making a decision are the sound quality and battery life. I'm assuming the battery life will be around 15 hours, which should be enough. And I bet it will sound similar to the toshiba gigabeat or whatever it's based on. As long as it sounds better than the ipod I'll probably get one, though that won't be too hard to do.