It is definitely scratch-prone. I've scratched my yellow 5c already - within 5 days of getting it, in fact. I've got a couple of light ones about a half-inch below the camera, then a small collection of scuffs on the opposite side, same height, along with some very, very light scuffs on the back that can only be seen when viewed at an angle in bright light. I'm blaming the bigger ones on a car mount, where the iPhone may have vibrated in the mount just enough to cause some scuffing. They're minor, but annoying to see so early on.
I'm contemplating picking up a case with the Apple case in the lead not because I'm in love with it but because it has that soft lining. My experience with the 3G and cases showed me that cases caused grit to get caught inside and cause damage in areas where it accumulated. So right now the dilemma is whether to let the 5c "age" naturally and enjoy the way it feels, or cover it up to prevent any more damage, light as it is right now.