I don't like it. I mean it is a great idea, but let's be reasonable. First, what if you fall? Can the iPod Nano's multi-touch screen display actually handle any kind of damage?
Second, it is more noticeable. Which is bad for some people who don't live in such good areas.
Lastly, though it seems like a great idea, what about the headphones? It would be annoying knowing that the headphones keeps being pulled from your ear every time you walk, or run. Why? Well, Apple's earphones aren't so long.

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Besides what I noted above, I would like to say it doesn't seem bad. I just don't like it.