It has 1160 square metres of climbing wall which reaches up to a dizzying 16 metres. It's suitable for beginners and the more experienced. They are also open quite late most nights (at least 9pm) and it costs $26 for casual entry including equipment. More information on their website.
They are definitely not the only game in town however. This is the most complete list I could find. Scroll down to the Sydney section for your climbing pleasure.