Plastic looks good
I like the plastic case of the 5C.
The phones don't look as elegant as the 5 and 5S, but when judged based on its own design merits, it doesn't look bad. It doesn't even look cheap to me, and the significant majority of phones from other vendors have used plastic on their phones, and yet they can still look and feel good. My favourite phone design in recent memory is the Nokia 920, which I think looks and feels better than the 925.
The 5C doesn't look nearly as good, but to say that the 5S looks better because it's plastic isn't something I agree with.
If the 5S had the same specs as the 5C, and was only $50 cheaper, my 1st choice would be the yellow 5C, then the "Space Grey" 5S, while the blue 5C would be my 3rd choice. I'm particularly fond of the yellow and blue.