Feder is a gracious and friendly host. I recommend guests to be able to speak some Spanish at least before booking with him, even though he does his best with English.
When I was there, the room was clean and neat, and the toilet was likewise. Feder was very upfront about his smoking, and told me that he would smoke with the extractor fan switched on in his room. I did not smell any smoke at all during my stay.
The house itself is well-located in the old town, near the metro station, and also the Mercado de la Ribera, in case you wish to buy groceries in the morning. I spoke with Feder and was allowed to use his kitchen.