Hmmmmmmm, having actually lived there, I am of two minds about it. In all the time I lived there with only one exception did I ever feel personally threatened (was followed by a group of three thugs who were talking to eachother in Potuguese about their plans for me - fortunately I speak Portuguese and was able to short-circuit their plans). That being said, I know Cariocas that have been robbed and car-jacked. I do know of tourists being robbed, however inevitably was almost always in Copa, and the people involved were inevitably doing something stupid (either knowingly or unknowingly). Rio is no more dangerous than any other major city per se, however there are definately certain areas where the unsuspecting tourist should not frequent and their are certain commonsense precautions which everyone should take.