The only flaw I'd noticed in my first iPhone5 (which developed a fault with the power button and had a mm or so of "play" if you pressed the screen near the volume controls) is that Gorilla Glass can't cope with sand. It's FAR from scratch resistant and one weekend at the beach in summer with it in my pocket 99% of the time left noticable tiny specs on the screen where the glass had chipped slightly.
I currently have my replacement phone in a rubber case with a screen protector and it's been like that since I took it out of it's packaging. I didn't even more than cut off some of the back plastic so it's going to be in as new condition till my contract is over with O2 and I can move to a reputable network.