Apartment was excellent and comfortable. Great location. We liked being in a residential area a bit away from tourists. The street behind the building had a nice, local feel.
Cleaning staff was very nice and very thorough!
Elevator was a bit unreliable but using the stairs were fine. Maybe you should mention the elevator in the back when people check in.
Parking lot at Ondaretta is a pleasant walk away, not too far, and never crowded (early July).
FeelFree staff is very responsive. Our friends who came from Bilbao Airport were very appreciative that they did not get charged for the taxi they had to cancel when they missed their flight connection (and the taxi was on its way to Bilbao).
Some times, though, because different people are responding to the emails, things fall through the cracks. I asked to add a day to our stay and was told it was ok. But a couple of weeks later I found out the extra day had not been added to the reservation so I had to email again. But this was not a big problem.
All in all, we had an excellent experience and all of our friends who stayed with us loved the apartment as well.