As long as you do it right they look nice. I had to repaint my MR7's because the guy before had painted them about 7 different colors(I'm serious, I stripped off gunmetal, black, red, white, and bronze that I can remember off the top of my head) and did none of it right. Just spray painted it on. Basically I got them for free, I just had to do all the work of making them look good again. Just waiting for my Ziex's to come in so I can get them on the car.
And I painted a friend's rims gunmetal a while back. They still look really good.
Just make sure you strip the clearcoating, prime it, sand it, paint it, and clearcoat it. And use lots of clearcoat. The more the better.