It was such a wonderful stay in Madrid :)
The room is a bit small but has a comfortable bed and enough space for storage. It has no keys. It also has a little balcony facing a bustling street, which is pretty noisy. But for me, that wasn't a problem. I actually enjoyed spending time on the balcony.
The common areas are well equipped and always kept clean. There are 2 bathrooms which are shared between the guests.
I've been there during the summer and Madrid gets really hot. There's no air conditioning, only a fan in the bedroom, which was fine for me.
The location is perfect: between Puerta del Sol and Calle Gran Via, a central area with lots of restaurants, shops, bars and tourist attractions within walking distance.
Rodrigo is a very nice host and easy to contact. I highly recommend it.