I had one and the first time I used it boarding my iPod and the h20 case went to the bottom of the lake in 60' of water never to be seen again. Luckily, h20 was nice and sent me replacement everything but I was still out an fairly new iPod which really sucked. Now, I only use it when floating around in the pool. This was the model which had a hard iPod case and an arm band. When I fell the case, headphones and the iPod evidently came out of the arm band and quickly sunk.
The replacement they sent was more of a self contained arm band thing which I don't use for boarding. The sound quality isn't that great... probably a trade off of being waterproof.