The apartment was clean and in good condition. The hosts respond to messages quickly and thoroughly. The wifi signal was weak in my particular room, but strong in the little courtyard and living room. As all other rooms are rented out, it feels like a mix of AirBNB and hostel, but the other guests were quiet and friendly.
The apartment is extremely centrally located, I waked everywhere, but a metro stop is only 3 minute walking away (if that far). It took about 10 minutes to get to Plaza Mayor, 15 minutes to El Prado Museum, and about 20 minutes to Atocha Train Station. There is a grocery store in the plaza with the metro (less than 5 minutes from the airbnb) with everything you could need, and the kitchen is well equipped for cooking. Each room has a shelf in the fridge which kept everything very neat and organized.