I stayed for more than 10 nights and I have some pros and cons that I have weighed a bit.
PROS:
1) The host is very welcoming, nice and proactive. They send you information at every step. I did not have problems finding things and checking in worked well.
2) It's really close to everything, so if you need to visit landmarks near the Centro, this is possibly one of the best located places in Madrid.
3) Towels, amenities and basic needs were covered, besides sugar, laundry detergent and cooking oil.
CONS:
1) If you are more than 175cm (5' 9'') tall, I would not consider this a good stay for more than 1-2 nights. The attic-apartments, like this one, cut into the roof are places to ruin your day when you just need to relax. I'm 190cm tall (about 6'2'') and after 10 days I felt like I was crouching every time I wanted to go to the bathroom. Boys need to sit down for wee, since there's absolutely no room near the toilet to stand up. Getting to the bathroom that looks like a cave, you need to watch your head since one beam on the way was about 15cm lower than the top of my head. Safe to say, I loudly sweared a few times. Additionally to get to the washing machine, was about the same effort and I felt like I could effectively use about 60% of this apartment. No bueno at this price.
2) No extra bedsheets nor any washing detergent was provided due to "people having allergies", for my over a week-long stay. I needed to get my own washing detergent from the shop and do laundry.
3) Trash can was way too big for small bags provided, so I had to invent something out of a bucket found underneath the kitchen sink. Not too big of an issue, but could have been handled by just giving it a bit more thought.