Hello!
I currently go to GRC Oatley senior campus, I just started my preliminary year there. What I can tell you is that it's quite friendly and this years cohort is very competitive. Possibly the best Oatley has had in a while. Go for a school tour and enquire about it, its a great school, especially considering its public.
The school is ranked quite low, true, but if you really care about your studies and try, you should be quite fine.
I think its a great environment. Come see for yourself!
Can always do well anywhere as long as you are prepared to do it
Not a bad school for public comprehensive category. But there's a wide mix between really bad students to average students to quite competitive ones.