I think the moonstone is more than a plain silver. I think it's a great color, and I typically avoid the neutral silver/gray/black/white/beige.
I don't get the fascination with the frozen colors - I think the matte colors look great on the rat rods, but it seems that trend has made it to mainstream, which I don't really care about. Call me old fashioned, but I think a car with glossy paint will always be more attractive than a matte finish. Any time I wash my car (or get it washed), I think WOW, that looks terrific. I shouldn't wait that long to wash it again. I don't think I'd get that same feeling with a frozen color.