Somebody very close to me (nudge nudge wink wink) is a native of the "Ciudade Maravilhosa" (and is multiracial, FWIW) and informs me that, in contrast to NYC, it is impossible to walk the streets of the city center at night, for fear of getting rolled by the wolfpacks.
The north side of the city is essentially one big ghetto, but, even worse, the wealthier neighborhoods in the southern part of the city often have favelas immediately adjacent to them, necessitating extensive security in the form of gates, burgler bars, etc., to say nothing of private security companies.
The cops are underpaid, understaffed, and prone to corruption. Thanks to the most left-wing judiciary in the western hemisphere (to say nothing of overcrowded prisons), making arrests is often a futile tasks, and muggers are routinely let go within a day after being caught. As far as the citizenry itself is concerned, they are scared sh-tless in terms of getting involved in preventing crimes, so even if there are folks in the vicinity of your mugging/assault, they will more likely run like hell rather than help you out.
Nevertheless, it has beautiful beaches, great nightlife, lovely ladies, and a largely friendly, hard-working populace. I will be going at the turn of the year with my significant other, and have been in enough "danger centers" to know what to do to stay out of trouble.
Thanks for the warning. I’m planning on going to Rio in July. At least my friend is a Brazilian.