My wife, daughter and I had an amazing time in Sydney and staying at Serena's place.
The location is great, it is walking distance from most tourist attractions in the city (if you love a bit of walking like we do - about 25 mins walking to Opera house, Darling Harbour). Supermarket is just around the corner. And if you are a Muslim looking for halal food, there are a couple of halal restaurants about 5 mins walk from the apartment.
Serena's apartment is nice and cozy, the kitchen is well equipped for cooking a simple meal.
Oh and Serena is very flexible with check-ins and check-outs; which is super helpful when travelling with a toddler.
All in all, it is a great place to stay if you are travelling as a couple or with a small child.