Very nice small studio, centric and well connected. You can easily walk to the city centre, but also have plenty of public transport options. Alvaro is super responsive, zero issues for the check-in and check-out.
The place is really clean, have all the small commodities like cutlery, coffee machine, reliable wifi, and so on. The bed is really comfy with fresh and spotless bedding. Same with the towels, fresh and super soft!
Just bear in mind that the place doesn't get direct sunlight (which to be honest, during summer is probably a blessing), so it can get a bit loomy in the afternoon. Also in the shower there's a small tendency for water to accumulate at the door's rim, so you need to be careful when going out to avoid spilling. Other than that, perfect spot to spend a few days in the centre of Madrid.