My wife, baby and I stayed here for two and a half months. The location was ideal for us. It's within short walking distance to numerous parks, cafes, restaurants, museums, grocery stores and shops.
The apartment is very functional, with everything you need for an extended stay: a fully equipped kitchen, washing machine, laundry drying rack, spare towels, fast and reliable wifi, etc. And the apartment is fairly quiet, given it's in a city.
The building manager, Lydia let us into the apartment and was incredibly nice. She was all smiles all the time even though we could only speak a tiny bit of Spanish, and made us feel very welcome.
The host, Natalia, was attentive and even let us borrow her baby bassinet for the duration of our stay. She also replaced a non-stick pot that had seen better days, and was easy-going when we accidentally broke one of the plates. A few things needed repair in the apartment, such as loose door handles, a broken towel rack and a cupboard hinge, but a repair person was sent within a couple of days to fix everything.
Unfortunately, after we left, the cleaner had some problems with the washing machine (a leak) and Natalia requested that we pay for it, which we felt was unfair as we had not encountered any problems while we were there and we used it in a gentle manner. In the end, after some back and forth, Natalia decided to cover the costs herself.
Overall, I would recommend the apartment. It is in a great location and provides excellent value for a short or extended stay in Buenos Aires!