We (4 adults) recently been there for 5 nights. It's a beautiful app (1st floor with elevator) in modern style and perfectly decorated and furnished (also in details). It's clean and everything you need is there. Very good beds. Perfect airco in all of the rooms. Decent entrancehall. The hosts are very polite, and the welcome was very warm and friendly. Nothing was a problem and questions were answered within no time. We got gratefull help in order to arrange a taxi on the last day to the airport. On arrival there were drinks in the fridge and other provisions stocked so no need to go directly to the supermarket. The citycentre is on walking distance (abt 15 min) and Metro stations at 5 min. The app is in a lively international safe neighborhood in a old part of Madrid with many little supermarkets and restaurants around. (one big supermarket within 5 min walking).
We will and can recommend everybody this app when coming for a stay in Madrid.