Cristina's apartment is in an excellent location. There are good local bars and tapas places in the surrounding streets and by the Metropol Parasol (about 5 mins walk away). It is then about 20 mins walk to the Cathedral / Alcazar.
The apartment is good for sleeping. The bed is quite comfortable; there are shutters; the air conditioning is good. If you are a light sleeper, you might want earplugs (there is a little bit of noise from surrounding apartments).
We found the apartment to have a bit more than all the basics (iron, good shower, stylish decoration). There were occasions where we wished more was provided (pepper, a toaster, a coffee machine).
The apartment is accessed by a key pad, so we did not meet Cristina in person. This meant the visit was a but impersonal (but would suit those who are arriving late). However, Cristina was excellent at replying to any messages - often within minutes.