I stayed at Esther's apartment 3 nights with my husband and 2 year old son.
She is really pleasant and welcoming. And she even organized a ride for us from the airport.
The apartment itself is really cozy, clean and spacious. It was equipped with everything necessary - kitchen ware, washing machine, soap, shampoo, towels, wifi, and even a phone to call local landlines.
So we really didn't need to worry about anything. There's a playground right across the street where Sebastian, my son, played with the local kids.
The neighborhood is really safe, considered one of the richest in buenos aires, I believe.
Tons of other parks around - botanical garden, zoo, Japanese garden.
The only thing that was somewhat bothersome was a neighbor that put on very loud music until late, but definitely not a deal breaker.
In a few words - great, clean place that I really recommend!
Thanks Esther!! :)