We had a great time in Lisbon. For us, this apartment is in a great location. It's on a very quiet neighborhood street, within walking distance to a lot of amazing restaurants and cafes, has a convenience store just down the block, and on a wide street that is very easy for drop-off and pick-up's (huge for Uber service which is also fast and insanely good value in Lisbon ) which makes needing access to Metros or buses completely redundant. The apartment is walkable to most of the main Lisbon city sights yet it is certainly not in a tourist area. Note, we are a typical family with teens, so able to handle hilly Lisbon; others with mobility concerns may feel differently. The apartment is also on a second floor up two sets of single-person wide stairs. The neighborhood feels safe and is well lit... actually even areas stretching outwards in various walking directions seem fine. We explored a lot by foot, including in evenings, and never felt uncomfortable. We used the place also as base for daytrips to Sintra, Evora and Cascais, all of which originate from different stations in Lisbon, yet it was very easy to get to the stations especially with Uber - Rossio station (to Sintra) is walkable, and so is Cais de Sodre (to Cascais) if one is not in a rush.
The apartment is ideal for a family of 3-4. The space itself is better for those who spend most of their time outside seeing Lisbon, and not needing an apartment to hang out for a large portion of the day when awake. The main bedroom is perfectly sized, though the second floor alcove bed is not really conducive for much more than sleeping/lying down as one can't stand up there (have to crawl into the bed). This makes the living area important and it is sufficient though cozy. Of course, there are also nice hangout spots just in the very immediate vicinity less than a minute away - lovely cafes and a small park with a drinks/snack kiosk - that one can go hang out if he/she prefers to.
Overall, no complaints and the location of the apartment made our visit to Lisbon wonderful. Francisco was communicative before we arrived and we had no issues. He was also accommodative with us checking-in earlier as our flight arrived in the morning (the apartment was not in use the night before). With AirBNB and individual apartments in older European buildings, one can be surprised by massive variations in quality and setting; fortunately for us this apartment worked out very nicely and the positives far outweighed any space constraints.