Highly recommended with caveats
It's on the 4th floor up a steep and narrow staircase. No lift.
The loft area in the room has a very very low ceiling. You can't even sit up over half the bed. It's also accessed via a ladder that isn't too stable. No offence but it's not for plus sized people.
The shower is very small. I have problem bending over in the shower stall. There's limited hot water, which didn't actually pose a problem. My own personal gripe is that the water is too hot and there's no way to adjust it cooler.
The bathroom is very clean, however due to the age of building, the basin and shower drain a little slowly and there's a perpetual foul sewer smell in the bathroom.
That said, we really loved our stay here! It's full of character. It's also very warm and cosy. Alberto is a wonderful host, really made us feel welcomed.
The location is great too, very central and near lots of food and drinks places. A useful tip - do not miss going down calle cava baja to Casa Lucio for the wonderful food and atmosphere. Also, just downstairs is a very famous shop selling the best espadrilles in Madrid. Go down early before the shop opens, or be prepare to wait in line for more than an hour.