I've been diving around Sydney for about 5 years now, and Abyss is definitely the best shop, club and dealer around. The extra service they give to their customers is amazing (free guided dives on Fridays and weekends, lunch included!!) and the staff members are great.
I recommend Abyss to all my friends who want to take up diving, because they are the best. There aren't many places around the world that match the service and I haven't been anywhere that's better.