A friend of mine powder coated just about everything, but he's not happy with the result. The finish is not really as shiny as paint nor is it as forgiving. You can't touch up a powder coated part. The coating is brittle, so if you tighten a bolt down a little more than generously, the stuff cracks.
It's probably ok for cars that don't get driven much, but for a daily driver, I wouldn't suggest it.