My wife and I stayed in Buenos Aires for 30 days and we felt fortunate to come across this little gem. Having stayed in many locations throughout the world, we have certain things we look for:
1) host communication - Hector is amazing, responds immediately to requests. He makes sure you are comfortable and goes the extra mile. He welcomed us with open arms and shared his obvious love of Buenos Aires and provided many ideas on places to see. Hector checked on us many times throughout our stay.
2) geographic location/safety - we felt safe at all times, no problems with pickpockets. Montserrat is an ideal central location to see all of the sites that attract many tourists. There are also several hidden gems like Palacio Barolo. This area is lively and helps you get the real feel for BA. There is ample shopping from convenience/grocery to souvenirs/retail. Also nearby are many restaurants of every cuisine and nightlife into the early morning hours. This is a secure building with a doorman 24 hrs and motion-sensored lighting.
3) accommodation cleanliness - For us this is most important. Like much of Buenos Aires, Hector's apartment is older but fitted with modern conveniences. It is very clean, no bugs and no pests. The provided linens and kitchenware were in great shape. Upon our initial tour, Hector noticed the cleaning lady forgot the oven and he immediately contacted her to correct this oversight. The apartment is on a very busy street but even with the balcony door open it is still quite clean because you are on the 6th floor. The building itself is very clean, maintained daily - everything from walkways to the elevator.
4) level of comfort/amenities - fully stocked kitchen with unusual items including a toaster, manual juicer, pasta strainer, washer but no dryer which is common in BA, WiFi (spotty at times, but we are heavy users), satellite/cable with many stations/movies in English, the bed is very comfortable (2 twins or a double with them pushed together and a provided mattress pad), the dining table is sturdy, has many chairs and doubled as a desk for us.
5) available transportation - walking is ideal in this area since there are so many points of interest nearby. We found the bus system somewhat confusing but the Subte (Metro/Subway) is very convenient, easy to use, and low cost. Access is within a block. There are taxis readily available just outside the building. There are two fares available, the normal metered fare or remise (pronounced "remiss"). This negotiated fare is good for longer distances.

We came to BA for work/pleasure. My wife and I thoroughly enjoyed our stay and are leaving with amazing memories, as well as a new friend in Hector.