We had no problem to check in and out: we arrived before the time planned and we could easly contact Josune. Flexible time when we got out.
The apartment is 15 minutes walking far from the center (casco vejo). We easly found parking in the street (but not free).
Bar, supermarket and other shops are near.
I think it's a good ratio between cost and level of the apartment.
Overall, we had great time in Bilbao and San Mames!