Our family group of 11 had a great time in Madrid and this apartment is a truly excellent base to explore the city. It is a safe and easy walk to most places in the center of the city and there is a metro stop just around the corner (La Latina on the green line). In the bunk rooms, which are along the street, there was a bit more noise from the sound of people outside, but it really wasn't too bad for being in the center of the city.
The pictures are all fair and accurate, and it was clean and tidy. Be aware though that for larger groups there is very little privacy. The main room with the orange sofa is connected to the kitchen so noise from one room bleeds into the other, and one of the "bedrooms" is also open and connected to the same space with no door - it's basically a bed in a hallway. Just be aware. The space could also really use another bathroom - even a small one with just a toilet. We had a number of challenging waits with 11 people.
Overall, I highly recommend!!