We (my husband and I) stayed for several months in Juan's apartment, and we really feel that he went above and beyond to accommodate us. Any time we had a question or needed something, he responded very quickly and made it a priority to help us and ensure that we were comfortable. The location is walking distance to the Ciclorecrovia (a large swath of closed roads reserved for biking and jogging every Sunday); La Vega (the largest market in Santiago); the mercado central (touristy, fun, and a good source of fresh seafood); and 3 major metro lines.
The building is very safe, with a gate and 24 hour front desk. The apartment has everything you'll need- a nice kitchen, living area, bedroom, ample closet space, and bathroom.
We recommend Juan and his apartment 100%. Perhaps the highest recommendation of all: we've already booked the same place again for another stay in a few months.