One interesting note: the 5C and 5S have a price overlap at $199. At that price, you can get either a 32 GB 5C or a 16 GB 5S. For those who don’t care about technical specs, I think the $199 5C is going to win.
I agree with John on this. Generally, I feel the people that would have purchased a new iPhone anyway will get the 5s, but at this price point, you may see some people switch for the colors.