Cristina's apartment is very boutique in style. Very elegant. You will never open the windows - it's just too noisey with traffic. It's perfectly located to a beautiful park (good if your a runner). Atocha train station is a 2 min walk, the museums are close too. Even though there's a lift there's a few steps to be aware of if knees are an issue.
There's 2 beds side by side, Netflix and if you need anything communication with both Cristina, Zarai is instant. I would stay here again in a heartbeat.