The walk down the hill from the Sheraton to Leblon is problematic, both because of the heavy traffic on the curved road and because muggings used to be common there due to the nearby slum called Rocinha, one of the largest in Rio. But in the past few years Rocinha has evolved into a relatively safe community with the installation of police stations and the expulsion of the drug loads who used to be the real rulers of the place. There is also a public bus that used to be considered unsafe for the same reasons. Nowadays, I would say that these alternatives are just as safe as anything else in Rio, but if you can get a yellow cab (not the hotel 'car service') the ride will be cheap and quick.