We spent 2 months in mario's appartment, everything went really well.
Mario was the most welcoming host I ever had, and he was very reactive to our questions. There are 2 bedrooms, one with 3 beds, and another with a double bed, and a sofa in the dining room, so 5/6 people can live here comfortably.
I would particularly recommend this place if you go in Buenos Aires in summer since it has air conditioning (in one of the bedroom and the dining room).
Finally, we had to cancel the last week of our reservation because we decided to go on a road trip in Argentina and Mario accepted to refund us all the week, which was a very nice thing to do.
Would recommend 100% !