Public transportation in Sydney means a massive train system that services the touristy and business-y areas and runs continuously from the city to places a hundred miles away, gigantic two-level ferries that cross the harbor, and a fairly extensive bus system as well. The trains are the most notable feature, allowing you to visit the mountains quite easily, and the train cars are an interesting double decker design with large capacity. The card you get to use the system doesn't cost anything (though it will only allow you to add set increments of money to it). There are various daily and weekly spending caps, wherein you stop paying fares after a certain point, notably a very low cap for Sundays to let you go nuts and explore.
The worst I could say of it is that some of the train cars didn't have good air conditioning, and if you want to go to the airport there is a ridiculous extra fee you get charged (which there are various ways of circumventing). You can do a lot without a car in Sydney. read more