The one time we used Julia St, 2 Carnival ships in port on the same day, our car and many others were broken into. When I told the parking attendant, he told me "This is New Orleans, what do you expect?"
Our daughter rode them with us at 2 and a half years old. It was great. The seat is wide enough for 3 passengers, they can stop to let you load, and they put a seat belt on her to secure her. She loved it, we rode it back and forth several times.
It was a great day, fun water activities and good prices on food and drink. We got there on a minivan from a tour company working at the cruise terminal. We paid them one price which included transportation and admission. Next time there we will probably hire a taxi.