It's a very nice place to stay! I would really recommend it. Perfect for sightseeing, everything is in walking distance. Metro is near and if you'd like to take a train, Sol station is just in 10 minutes walk. Very convenient if you want to go to other cities near Madrid.
Amazing for night life! Lots of bars, restaurants and even the street is extremely popular you won't hear a noise when you are in the apartment!
In kitchen you have everything if you want to cook. Shops are near. It was very nice to have coffee and tea in the apartment, as we came late and couldn't buy anything.
The best and I doubt you will find that in other apartments was all the information Gonzalo prepared for visitors. You have Madrid guides, lots of prospects with different tours, maps, events, sightseeing information and Gonzalo's personal advices on restaurants. That's was so great! We followed his recommendations and all restaurants were amazing! That was very helpful since there are many restaurants and it's difficult to choose. Gonzalo is a perfect host!
Definitely recommended!