Awesome location, especially for museum exploring! Make sure to check the museum hours before leaving as the Reina Sofia was closed on Tuesday.
Also, a lot of the restaurants and bars in the neighborhood were closed on Monday so finding an open spot was a bit of a hassle. Despite Spain's late-night dining times, most places close at midnight. We were there mid-June which is pre-European vacation time, so it might change.
The bedroom facing the street is not sound-proof, so bring some earplugs. At 7:00 am scaffolding was put up on the building next door, so it was very noisy in that room. No fault of the owners, but be warned that there is street noise and nearly every street in Madrid has some sort of construction happening, including calle Fucar. The rooms are dark though, so easy to sleep any time of the day.
The AC is a savior in the summer and a respite from the heat and there are three powerful units.
Nespresso (small pod) coffee maker is ok with a bit of finagling, but no sugar. The bodega a few steps away has most of what you need and if you're not in a huge hurry, check out the larger grocery store across the major street. If you are short, you will have trouble reaching the glasses that are WAY up high (I'm 6'/ 183 cm and I needed to stand on the stool to reach glasses.) Also, there is a dishwasher, but NO provided dish washer detergent, a few (only one clean) microfiber cloths to dry dishes, and no countertop drying rack.
Laundry is easy and has a built-in dryer but bring your own detergent or buy some.
The laundry drying line is out of the window of the interior bedroom but only a handful of clips so either use the dryer feature OR hang your clothes in the wardrobes to dry. The iron is fantastic and has a vertical steam option, making it easy to get out the suitcase/laundry wrinkles.
Some curious dark red stains on the kitchen walls (blood?) and the bathroom vent needs a serious dusting. The vent is LOUD and doesn't turn off immediately...it takes about 15-20 seconds to turn off after you've switched it off. There were also some random long dark hairs on the beds and in the bathroom.
Lock box by the front door was easy, but the street entrance was broken and never locked. I didn't report it to the owners while staying there, but did mention it in my private review.
Warnings everywhere about NO parties. We had NO parties and tried to be extra quiet when climbing the stairs to avoid any unwanted visits from the aforementioned grumpy neighbor. There is at least one very barky dog that lives in the building that we ran into on the stairs a few times.
We never turned on the tv, so I can't comment on that aspect of the apartment.
The throw pillows on the bed have seen better days and the upholstery on the kitchen chairs is iffy, but the apartment's decor is simple and tasteful. It took us a little while to figure out the multitude of the light switches, but it can be bright or dark, depending on what you fancy.
All in all, a fantastic place to stay, but if you're there for longer, make sure to purchase your own soaps!
I tried to mention/comment on everything I would have liked to know prior to booking.