For $79/month for 3 months and you get 30000 velocity points which can be valued at $300. A net $63 benefit.
For the $79 plan month to month sim plan, you get:
Unlimited text and talk national and international to 35 countries
Unlimited text and talk + 4GB roaming in Zone 1 countries(optus.com.au)
Free Optus Sport
Free Apple Music for 12 months
No contract free to cancel after 3 months