Perfectly adequate and inexpensive for spending a night and getting up early next day for the train. Housed in an old apartment building near Retiro Park it's a great location. There is a bus directly to Atocha Renfe at the end of the street.
You might have to wait a while for someone who lives there to let you in the main door, as there are neither any sort if keys nor are you met by anyone. Also Paloma wrote me over 30 emails, some with just a few words, to communicate location and house rules and how to get in(wait). But good value for your money.