Good overall location to Old Town and nearby Tram. Behind the apartment is a slightly "dangerous" area, so just advise to not travel around there over night and as always, stay alert while traveling.
Google Maps isn't perfect, but it is in a tall dark building at the end of the street. Hit the buzzer for 5th floor #11, and Issac will let you in or come down himself.
Very nice place inside, great bathroom and beds. Everything very clean and tidy. Great filtered water, and he supplied maps and tons of information about Bilbao.
Thoroughly enjoyed my stay. Issac's English is limited, but so is my Spanish. Together, could easily work to understand each other and have a great time. Oh and wifi was perfect too 👍🏻