Big Hostel is not a party hostel, but it is a place where you will meet tons of people from everywhere of every age. Free Wi-Fi is fantastic -- we never had a problem with the connection, even in the rooms. They offer free coffee and tea all day long. Free breakfast is basic (jams, peanut butter, toast, cereal) but it is pretty good. It is staffed by stay and work people from around the world -- they are all very nice and helpful. There is a layout of sunscreens you can choose from and use for free!
The location is perfect! Honestly, it is right down the street from Central Station. Very easy to find coming into the city (an eight-minute walk from Central Station) and it is easy to walk downtown from here (it takes forty-five minutes to get to the Opera House). As it's located within the CBD, it is perfect to get anywhere -- take a bus to Bondi, a train to Newton, or just walk everywhere. Staying here certainly can lessen the amount you need on Opal cards -- Sydney is a very walkable city.
Rooms and Bathrooms
The rooms are pretty standard dorm rooms. The lockers, which are in the rooms, are extra large, which will fit the largest backpack as well as daybag. The mixed-dorm floor has mostly guys staying there (first floor), and so while the washroom is mixed, it is generally in a state typical of men -- not very clean. Now the hostel has no control over what people do, but the guys' floor could use a more rigorous cleaning schedule. The washrooms are pretty standard with one room with three shower stalls and three toilet stalls.
The kitchen, lounge, and dining room is one big space with the kitchen off to the side. There are strict rules on doing your own dishes, washing, and drying, so the kitchen is generally quite clean for a hostel. The staff do a very good job in cleaning as well as everything is wiped down twice a day. The dining space can be a little crowded, as they are the only tables in the hostel so there are times with a few people with computers hanging there. It never seemed to be a problem to find a place to sit though so don't worry about it. There is a small lounge seat and a single free-use computer just out side of the lounge/kitchen area so you can Skype from a separate and comfortable spot.
Overall, this is a great hostel. It is fairly expensive but you get what you pay for. Also, we never saw cockroaches and no personal bedding is allowed in order to keep the hostel bedbug free.