I haven't seen a picture of the iPhone 5c that doesn't make it look like a cheap toy. The colors chosen are "apologetically plastic" (as his lordship Jony Ive has said). I'm certainly not an arbiter of taste, but they look tacky rather than fun.
Have any phone manufacturers made phones in car colors? Like a deep metallic blue? I think those would look sweet.
(And the official sleeves multiply the ugly. And they show the word "hon" (the middle of "iPhone") through their holes. That seems to indicate a lack of attention to detail.)