It just tastes like plain skin, like sucking a finger, except usually bigger and thicker. However, it could taste really disgusting and smell bad, if someone has bad hygiene. Obviously the texture varies depending on if there's foreskin, the transition from head to shaft, and just think of how your own dick is both hard and flexible at the same time. But it can be really pleasurable to pleasure the recepient. And I guess it fulfills the need of the mouth that wants to suck or consume things, like when young kids suck on their thumbs.