Plus:
Location: the location is amazing, just about 50 meters from Aliados Square and close to lots of restaurants and sightseeing hotspots.
Toys: our child was happy to find a collection of toys to play with.
Minus:
Noise: the apartment is located right in front of a huge construction site, just across the narrow street. We therefore had lots of noise from around 8AM to 7PM. It is a large building site. It is thus going to be there for a long time. Closing the windows and the blinds may help (a little) against usual street noise, but is hopeless for the building site.
Cold: the apartment has large single-glazing windows. It was thus very cold inside. Except for the small electrical heater in the bathroom, the is no other source of heat other than the AC units in the bedroom and the living room. However, it took them more than 2 days to heat the place up to a decent temperature, and yet it was still chilly. The kitchen has no heating at all, it was therefore very unpleasant to use (by the way, the water heater was leaking and thus not usable).
Old: the apartment is older than it seems on the pictures as a previous user already pointed out. Although it gives a note of authenticity, it has downsides. The windows are quite symbolic. They barely isolate from either the cold or the noise, even with the blinds down. The electric system is too weak. We could not use the hotplate in the kitchen at the same time with the heater in the bathroom without having a power cut.
Overall: the apartment is convenient to stay in, however, even for short holidays like we did (4 nights), these minuses tend to outweigh the positive points. Just for the noise of the construction site, I would not recommend.