We spend one week with our two 15-year old girls and enjoyed the little distance to all important sites of Madrid (everything is in walking distance).
The appartment is a little jewel, it is all very clean and nicely decorated. As it is on the last floor, you do have sun nearly all day (which for us, coming from grey winter Berlin, was fantastic and felt like summer vacation).
Walking up to the 5th floor was less exhausting than expected (eventhough I was struggling with LongCovid).
The only thing you absolutely need to be prepared to: the appartment is in the center of the city's nightlife (bars and clubs open until early morning). Therefore, you should absolutely bring very good functioning earplugs. Otherwise you might not enjoy the stay, because of very bad sleep (this is not Elliotts fault though; windows and shutters are of good quality).
All in all, it was a great and fantastic stay!