We really enjoyed our stay in Bilbao. The appartement is very spacious, even for 9 guys. The large kitchen und 2 seperate bathrooms were great for us. Everthing was very clean. Although it is not located in the fanciest of neighbourhoods, you can reach Bilbao's oldtown and also nice districts in the newer part of the town in just a few minutes by foot. Also, car rental for day trips is available at the train station right beside the appartement.
I would highly recommend this accomodation for large groups of friends or even two large families!