If you can recall when I first started the African trip blog posts back late last year, when in Johannesburg we stayed at the lovely Winston Hotel.
When we started to research getting from the airport into Rosebank where the hotel is located there were a few options, taxi, airport transfer bus or train. The train seemed quick and convenient and we were going to need to do this trip a few times so decided to go via train.
It really was easy, you brought a transport card to top up, found the platform and got on. Rosebank required a transfer, but one the train there were plenty of maps clearly showing this.
I don't think I would hassle with a cab or minibus transfer if staying near or on the train line in future trips. It was clean, quick, inexpensive and safe.