We stayed at Alvaro´s apartment for approximately two months (February/March) and were very happy there. The 3rd floor apartment is both spacious and comfortable, with good natural light and lots of windows for ventilation. We really enjoyed the residential feel of the Condesa/Roma neighborhoods and the apartment is an ideal base for exploring the rest of the city. Beyond that general statement, here are some specific things that made our stay so enjoyable:

COMMUNICATION—email communication with Alvaro was easy and his responses were always fast and complete, both before and during our stay. Since Alvaro is living in London, the apartment is looked after on a day-to-day basis by Arturo, the building caretaker who lives on-site. Communication with Arturo was also very good, although some fluency in Spanish is helpful in working with him.
SAFETY—security in the building is good, with double gates/double keys at the street level entryway. And we felt very safe on the streets surrounding the apartment, both day and night.
SLEEPING—the beds in both bedrooms are very comfortable. If you need complete quiet at night, choose the bedroom (with a king size bed) that opens onto the interior well/shaft that is away from the street. The other bedroom (with a queen size bed) faces the street and it does have some traffic noise at night.
WI-Fi—the wi-fi is good. It covers the entire apartment, except the bedroom in the back with the king size bed.
EATING—there is a good selection of restaurants within a 3-6 block radius. Every Tuesday, there is an excellent street market practically at your doorstep. There is also a very good supermarket about 6 blocks away that is open every day, until at least 10pm.
TRANSPORTATION—with metro/subway access around the corner, we could travel around the city easily. And, on the few occasions that we chose to use Uber instead of the metro, the ride service was very fast. Note that the best way to explore the Condesa/Roma area is on foot and you definitely should take time to wander the pleasant, leafy streets.
Ciudad de México is an amazing place! If you choose to stay in Alvaro’s apartment, you will have a great base for exploring all that the city has to offer.