What a great experience. My wife and I came here to start our honeymoon, and it was a perfect start. The apartment is centrally located, 15 minutes away from the museums, 15 minutes away from the main plaza. There are restaurants close by within minutes, there are bars within crawling distance. Let's just say that you cannot go hungry in this town.
Our host was gracious, and accommodating. she even helped us with our bags up three flights of stairs. If we ever come back to Madrid, we are definitely staying here if it is available.
With regards to the apartment, it is modern, clean, and absolutely delightful. You will find all the amenities you need, but who am I kidding, you will be out exploring all day anyways. Take advantage of the train station close by, we were able to go to Toledo on a half-day trip, and it was super convenient for us to board our train to go to Barcelona.