I've stayed in Bilbao for almost one month. The apartment is very calm, all the windows face the inner courtyard (therefore it might seem a bit dark). There is just everything one might need for a comfortable stay inside - dish washer, washing machine, fully equipped kitchen, spacious wardrobe room, nice bathroom.
The apartment is bigger than it seems on the photos.
There's a big supermarket nearby. Metro and tram stations are just right at the corner.
I would definitely book this apartment if I have to come to Bilbao again.