The apartment is very central with the main sights, restaurants and markets very close by. Unless you want to go to the parque de ciencias or the sea you can walk pretty much anywhere. It's also easy to make a day trip to Madrid via the AVE.
Inside everything was clean and the kitchen was pretty well equipped. The only thing we found was that it was noisy - I think this is partly because we were there at Christmas but some of it is the location (old narrow streets which funnel the sound, restaurant below that puts away tables around midnight, bins around the corner that were emptied around 2am). However once we had high-quality silicone earplugs we had no problem.