Location in Malasana is fantastic! Very close to Gran via and the city center. The studio is quite large, the furnishings are very nice and modern, and I found the bed to be very comfortable. The WiFi is very fast, and the furniture is quite comfortable. There is a nicely-sized refrigerator and nice dishes, utensils and glasses to use, as well as a Nespresso type brewer (no coffee pods were provided although it was not advertised that they would be). The windows in the living area (which are frosted) have room-darkening curtains to cover them as well. Nothing about this flat felt cramped, and it was very clean.
The street is not too busy and therefore pretty quiet most of the time, although you do hear the neighbors coming and going through the lobby/foyer off and on pretty much at all hours of the day. Also, the building's entry door does not close easily, so most residents try to slam it closed, which you can hear throughout the flat due to it's location on the first floor and proximity to the street. Also note that there is a limited amount of hot water, which I understand is common for Madrid (maybe 3-4 minutes for a shower).
That said, I had some earplugs handy and learned to take efficient showers and it worked pretty well. Overall, this place is very nice and comfortable and I would stay here again. I mention the noise and hot water because those are things that I am sensitive to.