I bought this for my hubbie after he lost the previous one! It's great (if a little fiddly at first to get the nano in) once you get the hang of it. Haven't had any of the problems reported on other brands about the plastic loosening and the nano dropping out. Great buy at a reasonable price. The kids love slapping it on everything too!
September 2013: OK, this item was great for the first 6 months, and hubbie found his original (and favourite) one a few days after purchase! After approx 6 months, it was a concern that the plastic was getting loose and you could lose the Nano whilst out running/at the gym/walking around, to the point where it went in the bin last month, having not been regularly used for the previous 4 months.
So, in retrospect, if you only need it for a few months, it's a great gadget, if you're looking for a long term holder, try something else!