Overall we enjoyed our stay at Carlos appartement.
The location is great, right next to Gran Via and close to 2 metro stations. There is always something to do and places open to eat.
The appartement is nice and clean. As it mentions it does not have air conditioning, but the fans they provide were enough for us.
The view from the windows is nice. For sleeping we recommend close the windows to cancel the noise, it works perfectly!
The couple of issues we had was that the wifi went away a couple of times, but came back withing 20min.
The washing machine leaks, apparently it has a little trick, but we struggle a bit with it.
We were a bit unlucky with running water, since the Madrid government was doing adjustments to the city, but Carlos and his family gave us a galon of water to help out with the issue.
The rest was great!
They let us leave our luggage before the check in time and we're always very responsive.
We have a little welcome gift when we arrived.
We would stay again here :)