Had an awesome experience with Jordana's Airbnb!
The apartment is in Flamengo, which is a perfect location a few steps from the beach, right between the touristic area (Copacabana/Ipanema/Leblon) and the business area. It's also at walking distance from the train station, although any uber from there will also be $2-$4. It has a grocery store crossing the street, and drugstores and many restaurants just at walking distance.
It is well equipped for anything you'll need during your stay. The private room is very well lit, with silent AC, good wifi and a comfortable working desk. The kitchen is also full of appliances you might need for a longer stay, and the living room is a nice space to watch TV. Private security/doorman from the building is a plus.
Jordana, the host, definitely makes your stay much better. From the moment you book the airbnb until you leave it, communication will be as easy as it can get. She's not only extremely responsive as to things you might need regarding the airbnb, but also very helpful when it comes to giving tips about how to make the most of your stay in Rio.
Would recommend!