SUMMARY: A lot more than I could've wished for, especially at this rate and with such friendly hosts. Do beware the room has no windows and is situated next to the bathroom.
LOCATION: Excellent location, spot on in the middle of Malasaña. Lots of little shops, bars restaurants etc in the neighborhood. No noise coming from the street. Perfect!
HOSTS: Very nice, friendly and generous hosts, who spoke some English which was great. They cooked for me and we went for a beer the first night. Friendly interaction with the other guests as well. Since there were no guests after me, they even offered me to stay another night for free, which was a nice gesture.
APARTMENT: The apartment was spotless and looked to be newly refurbished. There's a small living room with a tv and a well equipped kitchen. No dishwasher. The wifi works fine, but is not very quick.
BEDROOM: I had the room on the right. This bedroom is big enough for one, the bed had fresh linen and a mattress which sufficed although there were a couple of worn springs. There's a little desk and a wardrobe. At first glance it's great, and better than the picture! For me the downside was the lack of fresh air. The bedroom has no window (something not out of the ordinary in Madrid), and it is situated next to both the kitchen and the bathroom. No smells or too much sound from there, but the bedroom door had to stay firmly closed for obvious reasons. The bedroom did have high ceilings and a tiny fan which I left buzzing for a bit of fresh air throughout the night. Some noise from the neighbors next door but not too often.
SHOWER: The shower looked impressive but I did manage to get cold water two out of five mornings. I didn't mention it to the hosts, it might've been an easy fix. To me it seemed the boiler can only heat about 3-4 minutes of water and then stops to reheat for another batch. Also, the shower head was pretty low (1m75) and could not be adjusted.
CONCLUSION: I would recommend this place!