my mum and dad recently moved from a crappy satellite service to a fixed wireless NBN service with iiNet.
they went from 1Mbps to 23Mbps download speeds. in short, it is fantastic.
they pay $65 per month for 50GB downloads (more than enough for them), free installation and free modem. installation of antenna was painless and so was hooking them up.
mum and dad's house was not in the specified coverage area. they live in a valley between two mountains and the NBN tower is on one of those mountains. they did have line of sight to the tower, but live at the bottom of the mountain where it was located.
we spent about 6 weeks going back and forward with nbnco, providing them GPS co-ordinates of the house and in the end, they said that we could get the service. once we got that confirmation from nbnco, we went to iiNet for the service install.
bear in mind too, that even though you are near a tower, you may be ineligible to actually get the fixed wireless service.
i found it easier to go the nbn website (nbnco.com.au) and plug in your address and see what the result is. if you have any queries, give them a call as they will be where the isp will go anyways to see if you are in the coverage area or whether you are eligible. make sure you get a request number from nbnco when calling to make follow-ups easier.
happy to answer any other questions you have...