has anyone ever owned/used one of these? I'm thinking about getting one for christmas for someone but don't know if a) they actually work and b) there is a particular kind that is better

amazon review for the one i am looking at seem to vary wildly between "Great! Works a treat" to "Horrible - broke after 1 use" so thats not much help...
http://www.amazon.co.uk/Dolphin-Waterproof-1GB-MP3-Player/dp/B000V9F3C0/ref=cm_cr_pr_product_top