Location:
This flat is centrally located just north of Peurta del Sol near Plaza del Carmen. It's also right near the shopping district (Gran Via.) It was a 15-minute or less walk to each major sightseeing venue. The actual flat is on the second floor of the building, so if you have more than 1 suitcase per person or really heavy luggage, that might be something to keep in mind as there is no elevator. Javi did offer to carry our luggage up for us, but it wasn't necessary in our case. There is a little market on the same street to buy your essentials. On the other street there are a lot of cafes where you can grab a cafe con leche and a pastry.
Amenities & Furnishings:
The flat has an eat-in kitchen, with the living room space behind that. The couch converts to a fold-out bed, which I would categorize as mildly comfortable. There is smart TV in the living room that can connect to Netflix, YouTube, etc. The kitchen table is a nice size to seat 4 individuals. There is a small refrigerator, a stove top, and a microwave. The flat has great tap water.
The bathroom has two separate sinks, and great lighting. The shower has a nice rainfall showerhead, as well as a handheld showerhead option. There is a washer and dryer in the bathroom and you wouldn't even know it.
The bedroom offers plenty of closet space, with additional drawers to store your clothes so you aren't living out of your suitcase. The bed is extremely comfortable.
The windows in this flat are great at keeping out the noise from the outside. The wifi was easy to connect to and fast.
I wouldn't hesitate to rent this flat again or recommend it to a friend staying in Madrid.