Have a look at http://resources.news.com.au/files/2012/12/19/1226540/520169-dt-hsc-exams-2012.pdf - this shows all the schools that ranked highest in the HSC in 2012 - most are private or selective schools, so KH is one of the highest performing public schools in the state. One would also expect that the whole Forest area would be getting plenty of positive attention over the next few years, as the new PM Tony Abbott lives here!
The Killarney schools are also really well known for the integrated French programme, where all classes have a French-speaking extra teacher, who teaches the itinerary in French. So kids learn Maths in both English and French, etc. It is a huge attraction for native French speaking families, and also those who want their kids to be exposed to foreign languages at an early age - there is also Mandarin taught in a less intense way.