Pros:
Great location (right on the famous Plaza Dorrego)
The space was large for the price and had everything you could want
Pretty building with charming hallway
Owner put time and attention into outfitting the space.
Owner arranged for check in way in advance and is easy to reach.
Con:
My mother and I couldn't get the keys to work numerous times and we were repeatedly locked out and had to wait for the maintenance man to come who lived remotely (very sweet man but didn't speak English to help us to better understand the keys). The keys are old and have to be finessed just so and although I'm a lawyer and my mom is a teacher, neither of us are talented with old keys and it was impossible for us. After the 4th lockout, we decided to move to a hotel so we wouldn't have this concern hanging over our head. The apartment's owner did refund half our costs which was appreciated. The neighbor across the hallway tried to help us unlock the door a few times and she said that her boyfriend (who is from Argentina) has successfully helped other renters in the same situation by using a credit card and fiddling with the lock.
Another issue is that the top bedroom was directly over the 1st bedroom which was fine but noises carried because there was a handcrafted bench which was open to the ceiling below. This really wasn't an issue for us though.
Overall, this is a nice apartment if the owner is able to figure out more user friendly locks.