Apart-Hotel Serrano Recoletos, Madrid

Beware if you come with a car: parking is expensive. They have a deal with a public parking nearby, but only after the car has stayed 12 hours in a row do you get a second ticket you use to pay "only" 23 euros something for until a whole 24 hours instead of about 35 euro. Parking in the street is even more expensive (except that from 21h to 9h it's free, but it may be difficult to find a place).
Services are very few. No common restaurant or buffet or gym or anything (but wifi and tv in the room). Even the mini bar was closed when we were there. No supermarket advertised in its web. But you can buy stuff in shops (a nearby Carrefour is fine) and cook in the small room kitchen. You can do that for breakfasts (or go to any nearby cafeteria, as they themselves recommend instead of the "continental breakfast" they offer to take to your room). The small fridge is enough, but the small kitchen is very poorly equipped. No air extractor. No cleaning/washup stuff, napkins, etc. So you can cook simple things or heat your milk for breakfast, but how do you clean? Few cooking tools, but kitchen very usable if you bring some of your own.
The shower was tricky to stabilize water temperature, and not too much pressure.
The rest is all good: decent wifi, beds, etc.
No hidden charges (as cheap as advertised.because no parking I guess).
And, above all, a great location!