Very clean and is an excellent location and base for central Madrid; right next to the market of San Miguel and Plaza Mayor.
Andrea gave good tips which included drinking sherry with the locals in La Venencia and sampling the tapas in El Lacón.
I would also recommend eating/drinking in Casa Maria which is the first eating place in Plaza Mayor (on the left hand side as you enter the plaza from the apartment)
The directions could be improved by including how to get there by metro.
The nearest stops are Opera and Sol; Sol being the better of the two because you just need to walk west along Calle Mayor in the direction of Plaz Mayor.
We had a problem with WiFi not working the first night we were there but that was because one of the power adapters failed; this was rectified quickly.
We had an evening flight home and Andrea let us leave a suitcase in the apartment after check out time.