We visited Madrid with my parents in December. This apartment served us quite well during our visit. It was comfortable for the 4 of us, with plenty of space for our things.
We appreciated that we chose this apartment over a hotel because the living spaces were inviting and accommodating. It was nice to wake up in the morning with a full kitchen and space to enjoy the sunrise; whether on the awesome rooftop patio, or at the roomy kitchen table (note: there is no coffee maker, but it seems most of Madrid prefers instant coffee over brewed).
The location is amazing. So close to everything. The neighborhood surrounding the apartment is packed full of tapas bars and restaurants. We really enjoyed the bar downstairs; in the same building. Could almost be described as a dive bar, but the staff were very friendly and the tapas were delicious. We spent a lot of time in there. A great way to end the day on the way back to the apartment. The proximity to the Rastro was also a huge plus for us. It's so close that you could swing by the apartment really quick to drop off items purchased at the Rastro, and then go out for more.
We wouldn't hesitate to rent this apartment again if we are ever to return to Madrid in the future (fingers crossed).