I can not recommend Roberto and Juan's place highly enough. It's clean, beautifully decorated, and has a fabulous balcony and view of the Recoleta neighborhood.
There was a bit of a heat wave while I was there, but the breezes made it comfortable for the most part. However, when needed the AC did a fine job of keeping things comfortable.
One of the best things about staying there was how responsive Roberto and Juan were. I had a very late arrival time and they were there to help me settle in despite the late hour. Also, I had a small issue with the hot water and Roberto came out right away to fix it. Communication with them was always clear and easy.
Staying at Roberto's place was one of the highlights of my stay in Buenos Aires. I would definitely book his place again next time I'm there!