I have just signed up with 3 for 24 months (yes it is a long time) for mobile broadband. I can not complain about the price $0 upfront, $50 a month for 1Gb of traffic and while I had to give 3 customer care a couple of phones calls. The installation instructions were a little vague and because I was trying to connect within a hour of signing up somebody had to manually flip a switch, it was not a difficult task.
The good news is I now have the phone number of their Mac support centre, and the modem came with Os X and Linux drivers.
Speed is much better than the trusty old 56k modem I have at home, but not quite the shared 10 Mb link at work.