What a GREAT PLACE! We spent 10 days here in January. It was very hot outside (93F, 34C), and even hot at night. But the A/C in the apartment was great! It does not "chill" to freezing levels-- but it kept us comfortable.
The LOCATION is THE BEST. We took the Subte (Subway) everywhere. Rides ran less than 50 cents US, so it was an incredible bargain. We also took taxis at night. We were warned to always bring close to exact change, as some cab drivers gave old money (no longer accepted) as change!
Want steak? Our favorites were Sagardi (in San Telmo), Don Julio (arrive early, order entrecote, lamb sausage), Steaks by Luis (AMAZING and personal experience, advance reservations essential) and The Argentinian Experience (also AMAZING). Highly recommend all 4.
San Telmo market and plaza were great, but our favorite thing was to just hang out and watch the Plaza Armenia below! Lovely festivals, weekend markets... we felt "at home" all the time. Loved the local doggies at the Plaza, too!
We hope to return to Buenos Aires. We will probably plan our trip around whether or not this apartment is available. IT IS THAT GOOD.
Cons: This is a TINY space. Perfect for 2 people or a family w/1 child. We loved making our own breakfasts and dinners when we didn't want to go out. So relaxing. Not deluxe, but has everything you need. We loved it!