I've sucked cock before and "velvety hard" is exactly how I would describe the way the skin of a cock slipping against your lips and tongue feels when you first put it in your mouth, as well as the radiating warmth of it that spreads through you through your mouth and the warm, gooey feeling in your head you get if you're really into it.
Once it's good and wet though it just glides in and out of your mouth. And the flavor is a slight saltiness that's unlike skin elsewhere on the body. Sucking cock is really just as much fun as it looks.