Johannesburg is as safe as any major city of 8 million.
Safer than many.
For example, Saõ Paulo, New Orleans, Baltimore, Detroit all have more murders per 100000 than Johannesburg.
All cities have good, and bad areas.
I have lived in Johannesburg all my life, and never been mugged. I have a friend who has been mugged twice ... once in Rome, and once in London!
Use common sense, and don't do anything silly like going into an unfamiliar area alone, at night, just as you would never do at home.
If in doubt ask!
Follow this advice and you will be perfectly OK
PaulaA126 from Blackpool, UK, recently had this to say:
""4. Re: Walking from The Gautrain to Crowne Plaza Rosebank
Jan 29, 2013, 2:56 PM
Well after my Trip to South Africa i can say I feel more safe walking thru Rosebank than I do in a few citys in the UK.""
RElax and enjoy your visit, You'll be fine.
Edited: 1:26 am, January 31, 2013