I'd highly recommend Ruth's place, and found it to be exceedingly good value for money - it's close to the train station, walking distance to some fantastic cafes and restaurants, and I was always able to find a parking spot directly outside on the street.
Ruth has thought of everything in fitting the place out - things you never usually find at an AirBnB (sewing kit, umbrella etc). Also, the special touch of providing breakfast supplies (fruit, bread, milk, juice etc) was wonderful.
As per many of the previous reviews: the shower is awesome!
I'll definitely be staying here again on my next visit to Sydney.