The appartement of Eduardo is very nice and unique. As other comments said, you should not be claustrophobic to stay in the room but if you are not, the mattress is very comfy and with the quietness of the rooms you could stay asleep for a full day without noticing it.
The decoration of the upstairs is very nice mixing old and new. The kitchen is also enjoyable.
The breakfast is neither perfect, nor bad. It is enough to start your day and there is a lot on the table to cook for lunch/dinner.
The general equipments are modern and function well.
Finally, the localisation is very good, we had two days and a half in Madrid and it allowed us to see all we wanted to see, just using our feet and a bottle of water.