Matías' place is simply amazing. You really shouldn't bother yourself with looking around for other places if his place is available.
The location is incredible, and I say this as a person who lived in Palermo the month prior—sure Palermo Soho and Hollywood are fun, but I'd recommend that you don't live where everyone is partying.
Surrounding the streets of Cabello and Ugarteche, there's some real history to explore. It is surely the most convenient part of BA, hands down.
Access to busses is impeccable, and walking to restaurants and points of interest (parks, monuments, etc.) was an absolute breeze.
I should also note that not a single creepy crawly was found during my stay, which is a big relief compared to the last apartment that I rented.
Matías the man himself is very intelligent. His interests personally match my own, which made talking with him fun and enjoyable. I'd be delighted to stay in his place again.