I use the Armor-X as a holder and a protective case for my Galaxy SIII on the bicycle. The Armor-X is waterproof and protects the device against damage very well, but still allows full access to all ports and controls. The ports are sealed by caps when not in use. The envelope is in my experience impervious to splashes and short immersion - if they but longer dives withstands, I can not judge.
The included handlebar mount is a little shaky, the device holds well on bumpy safely on the handlebars. Too tight should the clamping does not attract, otherwise slipping the clamping screw.