First, what's great:
Luciana - she's the perfect host. Friendly, helpful, with top-notch communication. Location is great, security is 24 hours, and they actually do check people that don't live in the building. Apartment is decently equipped for short to medium-term stays. Everything you need and more is within walking distance. Internet is great too. People in the building are super friendly, but I think that's just how the Brazilians are!! :)
The cons:
The airconditioning was ridiculously loud. Add to that the busy street below (to be expected), and it's quite difficult to get to sleep. If there was some mosquito netting in the window, we would have opted to just leave the window open while we slept because the weather was usually nice and cool.
Also - in general, if it's your first time in Rio - it seems like hosts like to plasticate beds, pillows, among other things.