I stayed 1 month in this flat and it was great.
Cesar was very helpful with explaining where things are (metro, shops etc..)
The flat is great for 1 or 2 guests, very comfortable and very well located - you are basically smack bang in the middle of Buenos Aires so everything is very accessible.
The neighbourhood does not have the best reputation amongst Portenos but I had a great experience. I think it is more of an urban legend than truth. There's nothing to worry about!
After a couple of days I settled down and I felt just like home!