This apartment is awesome, it's close to pretty much everything you want do in Buenos Aires. We got all our questions answered right away, provided with information about places to see, eat and how and where to exchange money.
The view from Ralf's apartment is wonderful and it was great to spend some time in the evening on the balcony sipping on Malbec. The area is very safe, even at night time I have never felt unsafe.
I will definitely stay here again when I return to Buenos Aires.