Years ago, I had a task to match some Smurfs, which was a little unusual. I had to use metallic paints in some limited ways, which was certainly different for me!
I found that a lot of what I was doing with my glazes could be transferred to the very alien type of paint. It would certainly not me my first choice of material, since as a 'regular' two dimensional painter, there are no such things as metallic paint.
Since then, I have used metallic on other limited projects. I have taken to mixing them with regular paints, especially on terrain pieces. This gives some interesting results!