To me iPhone 5C looks like an iPhone 5 in colored shells. iPhone 5S is really cool looking and power packed. Given I already have a 4 and 5 in the house, I am not going to put my limited funds on 5S.
However I will most likely queue for next iPad which I believe is going to be out next month with most of the coolness of iPhone 5S.
I am impressed with the way Apple positioned and marketed the 5C. Not to mention 5C’s design and specs.