I received this as a gift, and figured I'd add something to the reviews here.
- As others said, the iPod fits VERY snugly in the armband, and the only opening is for the headphone jack. The side volume buttons are completely inaccessible.
- Very comfortable velcro strap, but it has a maximum circumference of ~15.5"... that means it should fit most arms, but be aware of that.
- I don't have any problem navigating on the iPod while it's in the armband, the touchscreen works well through the protector. But not being able to use the volume buttons is really, really annoying, because you can't adjust the volume any other way if you've set a playlist through the Nike+ app.
I keep using it because it sadly seems like the best available option after looking at the Griffin armband. When I put the iPod in upside down, the case is so snug it holds it anyway, and now I can charge/sync it without taking it out of the armband (but if it stretches out over time, this won't work). And if you use Sound Check while you exercise, the volume issue isn't so disastrous. But all-in-all, this design definitely needs improvement.