Well, my wife abuses her Lumia 710 by leaving it in her purse so it can bang around with her keys, wallet, coins, pens, lipstick, and whatever else she carries around in that sack. She does have a couple of small scratches on the glass. They would drive me nuts, but they don't seem to bother her at all.
I still have the original screen protector on that was shipped with the device. Okay, it's not actually a screen protector, but it serves the same purpose lol. I will have to remove it soon though, at it's starting to peel a tad at the side, still undecided as to whether I will put a protector on, however, I have always used them on my TP2 and it's always nice to have a nice brand new screen every now and again (when you change the protector) and to not have to worry when you get a deep scratch... on the downside, a screen protector will invariably scratch far more easy than gorilla glass, so it's more a case of whether you want to see the device on in the future as opposed to whether the scratches will annoy you or not.