My mate had a 5 and its chipped so easily. He was careful but ended up looking **** after 6 months. Is the colour applied directly on top of natural aluminium? I surprised when they tested it nobody picked up on this.
Neucase seems able to give a black matte anodized finish that stands up. Their housings are anodized metal, not cases.
There were also quite a few arguments here when Scuffgate happened by metallurgists stating that Apple wasn't anodizing the metal long enough and/or was not using the correct process. Because of that it was more of a paint type deal, which scratched easily and flaked off. It didn't bond with the metal, it just attached to the top of it.