This place is very good value for the money. The location is excellent: far enough from the busy touristy areas but very each to reach via public transportation or even walking. Plenty of options nearby for restaurants, cafes, supermarkets, and even a full shopping mall within walking distance. The restaurant/bar downstairs is a good option for tapas, and a few meters from the building, there is a good bakery for your breakfast "bocadillo", coffee, and croissant.
The building itself is a little run-down, needing a bit of renovation and touch-ups here and there. They replaced the hallway windows on all floors during our stay, which is a good first step. The elevator is very slow (and tiny), so we normally walked the four floors up the stairs.
The doorman is really nice and always attentive to help.
Rosario/Diana was very quick to respond to our queries. When the coffee maker broke, they sent a brand-new one within a day. They were very considerate to let us check in early after our long flight from the US. They also lend us a little desk for me to set up my remote workstation.
The apartment faces the back of the building, which is nice to avoid the noise from the big avenue in the front. It also avoids the sun hitting it directly, so it does not get too hot.
The apartment has all the basic necessities, including a dishwasher, A/C, microwave, and coffee maker, except it does not have a dryer, so if you plan to wash your clothes, keep in mind that you will need to hang them to try (they have a rack for that). The shower is tiny, so if you are a tall person, you will struggle a bit. Not an issue for us :)
We stayed for a month, so we made it our home away from home, and we fell in love with the area and the city in general.