microchipping

hey guys and ladies. when i adopted reese from animal welfare league they microchipped him for free and they said to microchip rocco itd be only 20 bucks and no monthly charges like everywhere else. so i was thinkin its a good idea especially with us moving and when rocco gets out hes not nuetered so he gopes crazy fast running marking everywhere. i persoanlly think its a good dog so that if they do get lost and go to the pound or whatever since they scan them they would be alerted its not a stray even if it has a collar. SO what do YOU folks think about it. just curious if everyone likes the idea or if there are those against it and why?