I spent the whole of February in Tomas's flat, and can honestly say it had everything I wanted. There was access to a swimming pool (during summer months), it was clean, the perfect size for me (though it may be cramped for more than two people), nothing went wrong, nothing was missing, and Tomas was always on hand to answer my questions and offer me advice.
But, presumably, you aren't going to BA just to stay in a nice flat, which brings me on to the most important benefits of staying there - location, location, location.
Firstly, the flat is right next to Ministro Carranza subway station, which is on Linea D - the easiest way to get into the centre of town. Also, Linea D is really busy most times of the day, but you're almost guaranteed to get on at this stop (which certainly can't be said for later stops).
Secondly, the flat is just off Avenida Santa Fe. North of Sante Fe are the parks of Palermo, MALBA etc. South of Santa Fe, and you're amongst the many great restaurants and bars - the beating heart of Palermo. Really, the location couldn't be any better. I had a blast there...
...So, thank you Tomas!