I view colored stones with mixed feelings. On the one hand, I've found something to make chests, cabinets, doors, and other stone-wrought items from that won't blend in with all my nice walls and floors. Fortress aesthetic rises as I can now use contrast, or give specific Dwarves rooms that cater to their preferred stones or colors. Perhaps one room has red-stone cabinet, coffer, and door, while another one has blue. It makes it easy to tell who has all three necessary bedroom furniture pieces.
On the other hand, this new something is a large, oval collection of stone I planned to make into nice walls and floors. Fortress aesthetic is ruined as I must find a new color to contrast with what I've blundered into... or mine through it all and build floors and walls out of blocks of the old materials, making expansion more difficult (moreso for the seizure-inducing flash of all those floors and walls on the deconstruct menu).
I like the idea of finding cool new colors of stone. I just wish I didn't find so damn much of it at once.
Also, I've noticed that sometimes stone colors differ by what you make out of them. Granite, for instance, is the same dark gray color as diorite when used for walls, floors, chairs, tables, and what-have-you. But granite doors are black, while diorite doors are dark gray.