I stayed at Daniel's apartment for 5 days. I was working while also visiting the city in the evening and weekend. The place is very well located, you can get to anywhere in the center of Madrid in 30min by bus or metro. Daniel communicates very fast and very well.
There are only small things that bothered me a little. The location was a little dangerous at night in the hall because it's an apartment alone, on top of the 7th floor, and the light wasn't working in the stairs, which were very tight to climb. Inside the apartment some plugs were not working, the wifi was very weak sometimes which made it difficult for me to work properly, and some parts were not very clean either.
However the apartment is well equipped, and I had a good time. I would recommend to stay there without problem.