Our house has a 7 year old standing seam copper roof on it. Installers gave us a 40 year warranty, but emphasize it would last long after the warranty ran out. Life expectancy is something in excess of 75 years. The ONLY worry I have is that the meth heads don't climb up on my roof and steal it.
This past spring, we had a big hail storm. Everyone in the area with regular shingle roofs ended up re-roofing their homes. Ours had ONE dent and no other issues.
I have some of the original paperwork when the house was built in 1961. The copper roof cost ALMOST as much as it did to build the entire house back then.