I just stayed here for a month (June-July, so winter season) and my priority was to find a place with a piano I could use for my work, but there are so many reasons this is a great choice for a short or extended stay in Buenos Aires. The kitchen is extremely well equipped and I chose to cook for friends more than to eat out, even though there are several excellent restaurants a short walk away. The apartment has no privacy doors between living and bedroom areas (so only really works for a solo traveller or couple), but is otherwise very well designed for all seasons and the heating works very well, the washer/dryer is convenient, and the bathroom is stylish. Comfortable bed and plenty of closet space. The living room couch is also very comfortable and the hammock is a bonus, as is the piano of course! The building has real character and friendly neighbors. There was a power outage of 15 hours one night but the neighbors assured me it's normal throughout the city and they're working hard to reduce occurrences - just be prepared.
San Telmo is, like the apartment, full of character and atmosphere. The main market is definitely the best place to get fruits and vegetables and also has good butchers and a delicious street parrilla after 2pm; there is also a wine/grocery store just south of Independencia on the same street as the apartment with much better prices than the supermarket. Subte and bus are around the corner, as are banks and the post office.
Ura was always a fast and helpful communicator and check-in was very smooth with assistance from the doorman. I hope to be able to stay here again and it definitely felt like home after a week or so.