Done correctly, they are a thing of beauty. And the more random the pattern, or lack thereof, the better they look.
A roof done in slate, with copper nails can last hundreds of years. And though the initial cost is expensive, consider that it’s as near a permanant roof as you will ever get. No regular replacement of the roof to worry about like asphalt shingles.
Considering the state of the world, I’ll keep to tradition and continue to install natural, green materials.