This place is not worth pricewise. It is not an apartment but a former shop with four bedrooms in the cellar. Since there are no windows, keeping proper temperature and humidity becomes a task on its own. Electric devices in the room are not sufficient to bring enough light, so it is also dark. To get to the common toilet you have to climb a starecase, which is quite dirty. Bathrooms and toilets are usually wet or dirty, because there are just too many people at this place. Naturally they do not clean after themselves and cleaning provided once in 24 hours is not enough. You can also hear your neighbours walking and talking.
It is indeed topographically central, but Madrid city center is not that big. The place is close to rather dangerous neighbourhood. Nice part of the center of Madrid with all the museums is 20-25 min walk. Interscity bus staitions and train staition are relatively far to walk also, so you need a public traffic to get there.