Katy H.
Yelp
Truly as good as it gets! Having stayed in hostels all over the world, I don't think anything can beat The Rocks at Sydney Harbour. Everything from the level of cleanliness, to the folks at the front desk, to the rooms, the views, and just the history of the neighborhood makes this YHA blow every other hostel out of the water. 
I have a twin sister who backpacked through Australia a year before I did. When she told me about this hostel I scrambled to book a room and found that on a few of the nights I'd be in town, they were all booked up. Damn! Having been forced to stay elsewhere in Sydney, I can guarantee that this is by far the best hostel in town. Perched atop a hill you'd be smart to catch a bus or cab to the hostel. If you're an idiot like me, you can also get lost and climb dozens of stairs with a heavy backpack. NOTE: Doing it my way will make you learn the hostels location really fast. Once I finally made it there, I never forgot how to get back. And I never took my backpack down that hill until I checked out! 
That being said however, the hilltop location provides spectacular rooftop views of the Sydney Harbour Bridge and the Sydney Opera House. It's totally worth the climb! And after eating some Hungry Jacks, I needed to burn off the calories anyway. 
If you're a history buff, an archeology buff or a geology buff - this is the hostel for you. The historic location of the hostel is really unique as they built it on stilts above the ground. With glass floors and glass walls at the ground level, you'll notice carefully placed signs and posters that show you what The Rocks looked like decades ago when people first settled in this neighborhood. You can even see artifacts that have been dug up as well as outlines and bricks leftover from old housing plots. It's fascinating! I really loved that the hostel wanted to preserve the land and make sure that travelers were aware of the history of the area while they passed through. There's even a little museum area where guests of the hostel can go and learn from a speaker and get a more in-depth story about the region, the history, the people, etc. 
The rooms at this hostel are great too. In an effort to conserve electricity, each room has a special key card. When you slip this card into a slot on the wall you can control the lights and the AC. That way when people aren't at home - the lights and air conditioning aren't working and there's no waste of energy being devoted to empty rooms. The kitchen is also state-of-the-art and enormous. Packed with everything you'd need to cook or prepare a meal, everyone has space for a cubby or a shelf to store their own food if they have any. Attached is a large communal dining space and seating area with cozy couches and chairs. While the space is clearly a hostel and not a hotel, it was a clean as a hotel and much cheaper. You still have to pay for WIFI access but that seems normal in Australia. Nothing was free!
Unless I'm on a romantic vacation with someone, I don't think I'll ever stay in a hotel in Sydney. I really enjoyed my stay at this hostel and wish every other hostel in the world could be this amazing. And I didn't even get to the huge TV room yet...!