This place is sweet. The location is fantastic, right on the Plaza 2 de Mayo in the city center. The plaza can be noisy at night, but the apartment is set back so you won't hear a peep. It's clean, nicely decorated, the air conditioner works great (I had a summer stay), the internet is blazing fast, the showers are fantastic, and it is well equipped. It is a ground level apartment so there are no views, but on the plus side the shutters can be closed for a completely dark apartment if you need to sleep, which I personally loved.
Daniel is an amazing host, friendly and helpful. I hope to stay there again on my next visit to Madrid. Great marks all around!