Mine had a small scratch/dint, out of the box, on the aluminium band just below the Home button.
Today I brought it back to the Apple Store where I bought it (Hornsby, Australia). The first guy I spoke to told me that it was perfectly normal for there to be small scratches on the iPhone 5 and that there was nothing I could do about it.
I spoke with someone else. This guy a took a little more time to explain that Apple will not do anything about small cosmetic faults like this on my iPhone. They will only offer replacements where the fault interferes with the functionality of the device. He said that there have been many people bringing their phones back over the past week and they are all being told the same thing - that nothing can be done.
When I pushed it further he spoke to his manager and came back to say that he could set up a Genius Bar appointment and they might be able to replace it with a refurbished model. He didn't recommend I do this though because he said the refurbished model will probably be in worse condition than my "new" phone. (I can believe this because when they replaced my iPhone 4 with a refurbished one the first one I got had a purple screen, the second the SIM card slot wouldn't close and the third had a yellow tint to the screen and they refused to try a fourth time).
I asked if I could get a refund and then I'd just buy another one. He said I can do this within the first 12 days but they probably won't have stock again for quite some time so it will be a long wait before I will be able to buy another one. Also, he said the new phone will likely have scratches too and may be worse then the one I have now. So, he recommended against it.
I'm not happy. It's only a small scratch but after paying $1,000 for a phone then I expect it to be perfect out of the box.