We, 2 adults + 2 kids (8 and 10) spent 6 night at Teresa's great apartment(s) during the busy days of the 2014 World Cup.
Teresa was the perfect AirBnB host. Available when needed, helpful, well-informed and highly discrete. Imagine the perfect host. Yes, that's Teresa.

The apartment is located in Santa Teresa, a "bohemian" neighbourhood, 15-20 minutes by car from Ipanema. There are quite a few tourists in the area but its far from as crowded as the main drag(s). We loved Santa Teresa for its architecture and (fairly) down to earth style. Unless you really want to be on the beach this is a fabulous alternative.

Teresa's place is newly built and the minimalistic design was perfect for us. The rooms are quite small (in essence they are bedrooms) but they've been cleverly designed and are hence comfortable. As the photos on AirBnB show there is a nice terrace just outside the rooms where guests can relax in the evenings. Just below there is a nice outdoor kitchen equipped with all the stuff you need to make breakfast/quick meals. Nice!
The kids really enjoyed the pool.

Santa Teresa is indeed located quite close to a few favelas but we felt completely safe to walk around the main streets, even in the evening. If you're worried about safety, Teresa will guide you.

You should be aware that Rio is a busy/bustling city, and although Santa Teresa is mainly a residential area, it's not an escape from the city atmosphere. The noise from outside (cars passing by, the busy Bar do Gomez, dogs barking etc) travels into the bedrooms. We slept well but do consider this if you're sensitive.