I had a nice stay at Fátima's apartment whilst in Madrid. It is in a residential area of Madrid, Prosperidad with good connections to the city centre. You can take a bus (number 9) directly to Salamanca or Sol fairly quickly (just over half an hour). The bus stop and metro station (Alfonso VIII) are only a 7-8 minute walk from the apartment, there is also a big supermarket plus restaurants and bars nearby.
The apartment was very true to the images shown on the site, it is clean and tidy with good facilities like the hob cooker, fridge and washing machine for you to use. The wifi is efficient and it also has its own secure, shared entrance downstairs.
The bed is a sofa bed but I found it comfy! Also, Fátima left a few things like coffee and biscuits which was thoughtful :)