I assume the best advantage to ceramic rims would be the ability to shed water easier due to their relative flatness. How much better are they? Does it make that much of a difference when breaking?
I don't think it's so much that they wick away water as that there's more friction to be had when wet. I haven't personally had ceramic rims before, but everything I've heard and read leads me to believe that folks who ride often in bad weather prefer them once they've tried them, due to easier braking.