The flat offers more than enough space for two or more people in the two seperate bedrooms. The flat is very clean and all the amenities that one expects are provided for.
We didn't have any issues with any sort of noise from any neighbours or construction sites.
One does have to walk up several flights of stairs to reach the flat, but it's nothing that isn't manageable.
Guillermo responds very quickly to all messages and his friend, Antonio, who takes care of everything on behalf of the host, was very welcoming on and efficient regarding the check-in procedure and being available for any questions (a big thank you here to Antonio as well for carrying my suitcase up all of the flights of stairs :-)).
The flat is well situated to explore the city, with a metro station within a short walking distance, a 24 hours supermaket on the same square and lots of other amenities around.
Definitely a flat I would stay in again in the city.