Great find in Bilbao - just on the edge of the Old Town, 2 mins from a large, well-stocked supermarket, and a short walk from the main market and a tram stop.
The apartment is very comfortable and has everything you need - the kitchen is particularly well-equipped and proper cooking is possible. Other than the standard muffled noises from other residents in the block the whole apartment is quite, especially at night. Sarai is a friendly and responsive host.
The only slight drawbacks - perhaps for some people - is that the apartment is at the top of a short but extremely steep incline, and that there is no air conditioning, so it likely gets extremely warm in summer.