hval
Sorry, I was not clear enough in my post, but I was referring to a screen cover.
The Otterbox case I use is the 'Otterbox impact case'. This is not waterproof, but is fairly thick and has built up corners with impact absorbing ribs inside (so it is not just solid). The only problem I get with this case is that it is harder to touch the extreme edges of the screen, and especially so when wearing gloves, as the case is fairly thick either side of the screen. For full waterproofness, and with an ability to still use the phone, I keep it in an Aloksak (as I would with all gadgets).
The screen cover was bought over the internet, and was sold as being non reflective and highly scratch resistant. One month after fitting the screen cover, a framed picture fell from a wall in the house, bounced down the stairs which broke the glass on the front, and then this broken glass hit the screen of my iphone! The glass fell at least one and a half metres, and landed sharp edge on to the screen. I did have to pick some small shards of glass from the surface of the cover, but otherwise it was fine. I replaced the cover (they came in packs of three), and the original screen underneath was still perfect.
As a further comment on my phone use, I keep the phone charged (when away from home) using a power monkey explorer charger. This has world wide plug adaptors, a 12v car charger, adaptor tips for my other electronic devices, a reserve battery giving one and half full charges as well as a remote solar charger. The solar charger has powered my phone for several weeks at a time, even in the cloudy British weather!