It's probably the cheapest place to stay in Madrid, and being in the middle of Nuevos Ministerios, you won't get a better deal.
However, it's a Hostel, it's going to be noisy and crowded.
I was given a bed in front of the bathroom, which is not great really as there's nothing in between so when someone opens the door, you get the light in your face and all the noises & smells.
The curtains intended to give you privacy are really poorly made. In the best case, you can cover 60% of the bed, and that if one of the other people in the bunk bed does not move it, as it's a curtain for 3 beds instead of having one per bed.
The last thing, is that the girl who attended the place was also sleeping in there and started sending and listening WhatsApp audios very late in the night with no respect for the rest. It's not like she did it all night long, but that area is supposed to be to rest and telephone conversations should be done in another place.
TD;DR: Location, location, location.