First, Perla's apartment is enormous. Even bigger than it appears in the pictures. My entire family stayed here for a week, and we felt very comfortable -- there was plenty of space to accommodate all of us. The kitchen is very nice, the dining room table is big enough for eight people comfortably, the living room has much more space than we even needed, and there are two good, fully functional bathrooms (and two minimally functional ones). It was perfect for eight people for one week.
Second, the location is perfect. Toward the east end of Ipanema, closer to Copacabana. There are hundreds of shops and restaurants within five blocks, and the beach is only three blocks away (as is the lagoa).
Third, Perla was an excellent host. She was flexible with times and very quick to communicate. She is also perfectly bilingual, which helps when needed.
Our only complaint was that the air conditioners in the living room seemed to be on their last legs, leaving the living room a bit too warm to inhabit at times (it was in the 90s the entire week we were there). But the bedrooms remained nice and cool throughout the week.
If you have a group, you can't do better than Perla's place -- the combination of price, size, and location are almost impossible to beat.