This watch case is very good.
The case unscrews for the iPod Nano to be inserted and then screws back together. This means that the Nano wont fall out like the clip in alternatives. The screws are metal and not plastic. It comes with a 'screwdriver' but this is poor quality, however it is easy enough just to use a normal smaller sized screwdriver in it's place. The description does not say a screwdriver was included so no real disappointment there.
The length of the strap is quite short. The full length including the space for the Nano is 24.5cm, however the circumerence from clasp to last hole is 21.5cm. This means that the maximum size wrist that this will fit is only a circumfirence of approximately 21 centimetres. The rubber strap is quite chunky being a thickness of 4mm.
I bought this for long plane flights as I travel a lot. The watch strap was ideal for this if I remembered to fit the Nano in the case before leaving for the airport. The gap at the side of the case allows the headphones jack to fit. The length of the strap lets this case down as it will not be suitable for people with above average wrists.