Well, it is certainly not a 5 star hotel, as you claim in your post elsewhere, but few hotels in Brazil really match that US/EU star system. Look on Trip Advosor for reviews from people who have actually stayed there.
As for location, IMO São Conrado ( where the hotel advertises its location) is a bit far out of the area to easily access most tourist sights (near hang gliding though), but not out of the question. There is a large, popular mall very close by.
But Rocinha is practically middle class these days, with foreign investors buying up lots and B&Bs (pousadas and hostels) opening to cater to tourists. A good resource regarding the community is Zezinho, who lives there, gives tours in English, and sponsors social projects.
www.favelatours.org. Note: Many well off Rio residents demonstrate prejudicial attitudes toward residents of these vibrant communities, which ensures they remain marginalized.