The stay at Carmen's apartment has been really, really great! We can only recommend to stay here, while in the city.
Carmen and her son are really friendly hosts, they give you recommendations or your privacy where necessary.
The location of the flat really is the best. It is close to walk to all major sights but is quiet and located in a little side street at the same time.
The room is small, yes, but equipped with everything you need and the whole concept seems to be really thought through. The fridge is really good to have a cold drink or storing things. The bathroom is only separated with a fold-away door but this didn´t bother us.
In case it gets too warm the room has air-condition, which was quite perfect during our stay.
As said before, I can only recommend this place, as there were really no downsides for us.