I had a nice stay in Mexico City and Lily and Luis' place - the location is very central and everything you might need is in walking distance (restaurants, cafes, bars, shops, etc). The metro (subway) is a 10 minute walk away which is very convenient. The room and apartment itself are great - the apartment is on the top floor of an older building that's been remodeled on the inside in recent years (facade is the original one), so it's fairly modern. Inside the apartment there's lots of natural light and plants, and there's a patio with more plants, some chairs to sit on, and a nice view of the city. There's a security/door guy at the main entrance, so it feels very safe coming and going at any hour.
Lily and Luis are very nice hosts who were a pleasure to talk to and with whom to discuss where and what to do in Mexico City (I was there as a tourist) - they've been living there for a while so they know a lot about the city (so much so that I did not feel I needed a guide book, which I hadn't bought for this trip anyway because I never got around to it).