With friends and family, we  celebrated the 60th birthday of my father in law. We could have gone for the ala carte restaurant but found the menu choice for the Buffet much more suitable. We had two tables by the windows 18 of us in all and fortunate that it was a clear a lovely day, so the views were spectacular. I wasn't expecting the food to be brilliant we really just wanted to eat and celebrate up in the tower, but I was pleasantly surprised, the food, selection, choices were much better than expected and all looked fresh and served hot. There's an excellent selection cold meats and some delicious deserts. 
We had a lovely long lunch, and sipping on some excellent wines whilst sitting comfortably watching the city below bustle on, and the grand views ever changing with the slow revolve of the restaurant. The service is efficient at first  especially with the first drinks, but it dwindled and every other bottle I wanted I had to seek out a staff member or go to the bar. My sense is that they are so used to serving quick bus tour groups that it's a quick in eat and forget, they need to realize not one service type suits all groups, there are Australian Sydneysiders that will celebrate a function and require on going service. This of course may not be an issue  for couples or smaller groups of four or six.
Overall a lovely day excellent food and fantastic views. Great photo opportunities.

Approximate cost: $37.50