They are a good place to put an early base. Start with ladders to get off the ground. As you spiral your rooms around the rock, raise each level by half a wall and it will be tall enough to keep you from bumping your head as it turns around. Put your campfire at the top of the rock with a chimney. It will be immune to raids, except for trolls which might be tall enough to reach. You'd still need a ditch to keep them from getting too close.

You can fit your smelters and a garden inside the circle, but it might be too small for animal pens too.