Arantza's apartment is an excellent base for exploring Bilbao. The apartment itself is just as described. The beds are very comfortable with good sheets, and the kitchen is well equipped for a short stay. Arantza kindly left plenty of useful extras such as big bottles of shampoo and shower gel, plus milk and breakfast ingredients in the fridge. As other guests have mentioned, it's a bit noisy late at night due to a small bar opposite, but if you want to stay in the heart of the Old Town, then I think some noise is inevitable. We were expecting this thanks to previous reviews. The main bedroom is a little dark due to surrounding buildings, but there are plenty of lamps/lights, and it's good for sleeping!
The apartment is directly behind the Cathedral where there's picturesque little square with a few pavement cafés, and all the atmospheric streets of the old Town are right on the doorstep. If you have a car, you can't park or pull up outside, but it's only a 6-7 minute walk to the main car par . However you don't need a car in Bilbao.
The check in was seamless! Arantza kept in touch during the day by message/email, and then met us at the apartment to explain everything. All in all it was just right for us and good value for 5 people. Arantza couldn't have been more helpful.