We use Telstra, it it dose give the best coverage as we travel around OZ, and most of the time we can get pretty good reception, except when we are in the middle of the Outback a couple of hundred K's either side of nothing.
We do have the occasional problem with our 4G Wireless set up, but have to admit, each time it was sorted ASAP, and we were satisfied with the service, maybe we are just lucky.
Leon