Looks to be the same deal found here: https://www.ozbargain.com.au/node/617020
Pretty good if you're a bit of a heavier data user. If you happen to have an iinet internet account the $15 gives you 80Gb a month
Edit: As mentioned in the comments iiNet are now using the Vodafone network
Currently paying 18 a month for 50GB with circles.life but this is a pretty close second.
Seems the real deal is if you're already with iinet though.