I stayed at Sofía's for a month while waiting to move into a permanent place in Madrid and it was a lovely, homey space. The rooms are cozy and I had fun looking at all the eclectic decor. The living room has a spectacular view of the sunset and the kitchen was fully equipped with everything I found myself needing (as far as basic cooking utensils/equipment).
It's a bit of a commute to the center, but the apartment is located close to a metro stop so I never had a problem when I needed to travel. I would highly recommend booking a room at Sofía's for your long term stays in the Madrid area!