Positive : Nice and clean appartment, very well located in the center, well equipped. The owner is very helpful with any of your requests.
Negative (cannot be improved) : no elevator, no parking
Negative (can be improved) : water heater cannot heat enough water for more than 2 showers in a very short time.
That being said, we had a very nice stay and strongly recommend Sevilla in December if you want to escape the cold (we had 19 to 20 degrees during the afternoons in January)