This is a great place for a short term rental, if you are a university student or on a short term work assignment in Bilbao and need a place to stay that is clean and quiet. It's not a great place if you are a tourist., especially if you are traveling alone. You will have to be prepared to enter the building from below street level, and go through a dark corridor past an underground parking garage to get the the elevator. Also be prepared to find your own way around the neighborhood to grocery stores and restaurants, as there are no materials from the host to guide you. You will be in a large apartment that other people are also occupying. You may or may not meet them - and they are coming and going throughout the day and night. There is no breakfast provided, and the only coffee or tea available has been left behind by other people who have stayed and are now gone. I stayed for six nights and was provided with one well used (but clean) bath towel and one hand towel. If there were fresh towels someplace else, I wasn't told where they were and didn't find them in any convenient place.
The host is offsite, and her mother will meet you. However, her mother doesn't speak much English, speeds through instructions about the three keys you need to enter the building and apartment, and will not be available to answer any questions for you about the apartment or the city. You may even be asked to take out the trash.
It's an amazing location if you are in Bilbao for The Guggenheim, as the museum is literally a five minute walk away. While I enjoyed Bilbao, I wouldn't stay here again.