I was actually amazed that Apple completely missed the ability to use touch when you weren't looking at the device.
It's terrible if you want a hardware button to skip a track, but it's usable for basically any iOS app with standard UI controls - including web browsing - which a hardware button isn't.
I've never seen a Zune in person - do you just mean it has lots of buttons for all those tasks, or how does the touch interaction work on it without individual hardware buttons?
My ideal is that we shouldn't always be aiming for items on the screen to interact with. We've traded hardware buttons for software buttons, even though the ability to recognize things like swipe now exist and are much more natural. With a button, I have to hit that exact spot. With more natural movements, like swiping, I am creating an action over a more general area. I don't have to be so exact, and therefore, I often don't need to look at the screen at all.
On the ZuneHD, it works like this, swipe right to left on the screen is skipe forward a track, swipe left to right is back. Swipe up is volume up, swipe down is volume down. Hold the right side is fast forward, hold the left side is rewind. tap the center is play/pause, tap bottom left corner is shuffle/unshuffle (though this is a visual button, it is fairly easy to hit without looking at the screen).
Unlocking a ZuneHD is the same as a WP7 (though many people haven't seen those either). You just swipe up on the lock screen and it unlocks.
With all of these interactions (excluding shuffle), you aren't aiming for a button, just a general area on the screen.
In comparison with the iPod Touch/iPhone, to unlock, you are targeting a fairly specific area at the bottom of the screen. Easy to miss the swipe area if you aren't looking. On WP7 the whole screen is the swipe area. As long as you start at the bottom, and swipe up.
Same with skipping tracks, on iPod Touch, it is a forward button on screen. You have to hit the specific spot. With the ZuneHD, you just swipe across the middle-ish area of the screen, and it will go forward the track. You aren't aiming at a specific item to interact with. It is all a very natural feeling.
This was one of my big disappointments with the iPod Touch. After the original iPod was such an amazing design for navigating and playing music, Apple told us about this great new touch interface and how we could swipe our fingers across the screen to interact, and how it was all so natural. But the swipe interaction was only on coverflow, which is somewhat useless. They missed the opportunity to make swipe a key navigation element in iOS.
I feel the same way about iOS apps today. Why do I have a back button at the top of the app. The back button slides a panel from left to right and shows me the previous content. Why am I aiming for a target at the top left (rarely comfortable if you are holding the phone in your right hand), rather than swiping across the screen and sliding the panel?
The swipe interaction isn't the most intuitive interaction for new users navigating around screens or other digital content and Apple seems to have used it for content that's derived itself from physical content or pages, such as books or images. If Apple were to use swipes as OS wide navigational gestures, it would preclude the use of swipes in app-specific contexts
pedalpete is still right though. If you tap the center of the screen when playing the song, you get an overlay that is separated into quadrants. Tap the top of the screen, volume up. Bottom, volume down. Left, previous track. Right, next track. Center, pause/play. I never look at my screen.
Fast forward a week or two after getting the HD, I was able to control the device almost as fast as the origin Zune in my car (without looking at it). It just felt somewhat natural, the way the placed the buttons. Didn't put too much thought on whether or not the positioning was partially intended for quick use.
I did, and though I like it, I don't think most of the apps have that same natural feel for navigation that the HD was able to acheive.