Noumea is a nice place but very expensive by Aussie standards. Also, areas outside Noumea are not recommended to visitors since there are still some disturbances by independence minded locals in the central and northern part of the island. From memory there were 3 flights per week from SYD but I can be wrong on this one. Maybe it was 3 QF or codeshare flights?

So, it really depends on what you want to do on your vacation. If you want to relax by the resort pool with all meals pre-paid then it's a good place, if you want to get acquainted with locals and their traditions then there are some safer islands not that far away.