First up welcome to the NBN it brings many good things (but in some cases it can be a hassle). Hopefully you will have a good experience. To answer your question it depends on what you want. The NBN arriving gives you several options:
1) I take it you're currently on Optus cable?
2) Paying $80-$100 a month?
3) Are you still on contract or month to month?
4) Do you know what technology your NBN is (FTTN? Cable?)
5) If you stay with Optus they will just move you to their $80 a month plan.
6) This plan is 25Mbps download (unlimited data). Comes with a FetchTV STB.
7) This will be a new 24 month contract
😎 Unfortunately it doesn't come with free phone calls. Its $20 more a month for free calls to all phones in Oz
9) If you want to boost the speed from 25Mbps to 100Mbps then its $20 a month more.
As a second option you are now free to choose any ISP you want to provide the NBN. Your Optus contract ends when they disconect your sevice (with no penalties). You can research any other plans on offer if you want to find a better match. Optus used to be the main option because they owned the cable exclusively. But now every ISP can use the NBN cable to provide data to your house.
What sort of usage do you have now?