Nice place to stay for a few days. The room (and the entire flat) is not that big and a bit dark, but quite good for a single person (or a couple if you don't need much space).
Carlos and his roommate are friendly, helpful people! If you don't speak spanish it is a bit hard to communicate but we figured it out 'cause Carlos speaks a little bit english.
The area is good: The metro station with two lines is just some foot steps away and there is a supermarket right across the street.
All in all I had a nice stay! Thanks again!