I stayed at Hostal Acapulco with my family just this October 6-9. And If ever I would go back to Madrid, I would definitely stay here again.
When we got there, we were earlier than the check-in time but we were able to leave our bags near the reception area (they don't have baggage room... too bad). When we checked-in we were not disappointed. The quadruple room is very big, nicely furnished and has a big bathroom with all the basic necessities like shower cap, soap, shampoo etc.
The location couldn't be more than perfect. It is very near Puerta del Sol (where we start the Madrid Vision Tour Bus) and Gran Via (where we like to walk at nights).
The people at the reception are very nice and you are assured of the security since there is always someone at the reception area. I like Javier! He's the best!
The free DSL internet at the reception is an added bonus! And if you bring a laptop you can tap because their internet is wireless!
All in all, it was worth its value and more. I am a very happy customer.