Samuel's place was beyond perfect. So much so that our only regret is that we couldn't stay longer.
The place itself is as good as advertised, and even better, with all the amenities you could ever want and then some. There are fully-stocked groceries and pharmacies right around the corner as well.
The terraces themselves are even better than described. Samuel even rushed to perform some of his planned improvements before we arrived, and I can't emphasize enough how much this made our morning breakfasts and evening family dinners on them that much more enjoyable. The sun you get, and when you get it throughout the day and into the sunset, could hardly be improved on. On a clear day you can even see the mountains beyond the horizon.
Location-wise, we could not have asked for something more optimal : right next door to the friends & family we were visiting. I can't comment on the logistics for getting to the city center as we didn't do it much ourselves, but taxis and Ubers abound and we were at most 15-20 minutes from anywhere we wanted to go in the city, or otherwise just a bus and metro ride away. Furthermore, as a runner, there are beautiful locations nearby for daily runs or even just for a walk, notably Juan Carlos park which is full of beautiful vistas.
Samuel was most responsive and helpful - beyond professional. Samuel's grandmother was there to open us the door when we arrived, and was most charming and lovely (thanks again!).
If Samuel and family will have us, we will be returning as often as we go back to Madrid to visit family and friends there.
PS. As a general advice, coordinate with Samuel ahead of time as instructed for best results, or make sure you have a good data plan if you are going to be using North American roaming plan as I did (lower priority for local carriers). Or better yet get a SIM and local plan as most people do for longer stays, and much less expensive. To clarify, WiFi in the unit is perfect, this is about when moving between buildings in the area and Madrid in general as some cell towers appear saturated, if you want the best connectivity.