As we were only for one night in the apartment, our experience is of course limited. However, the apartment is just great! It is located near the Hercules avenue (more of a square really), and from there you can walk straight through the shopping streets like Calle Serpies to the major sights like the Cathedral and the Real Alcazar. To reach it, you have to know your way (use a good map or app, or a taxi). It is approximately half an hour walk from the bus station near the river (from the railway station: 3 quarters to an hour, certainly with luggage).
The apartment is at street level, and some noise can be heard at night with the windows open; however the airconditioning does work perfect (so you can close the windows). We really appreciated the available space (my wife and I).
Although her sister gave us the keys (she was cleaning the apartment as well), Rosa came in the evening to give us some Jamon Serrano, as we had to wait a few minutes before we could enter the apartment. Although we had spoken her only that time, Rosa was very nice and supportive.