Overall, this stay was okay, but there are several "quirks" at this apartment. No air conditioning (which admittedly was clearly noted in the listing) means you should be careful if renting in the summer. Our spring stay included 90+ degree F temperatures, and while the apartment cooled down at night due to the cross breezes through the windows, it wasn't very habitable in the sunny afternoons.
Odd storage: there are several closets/cabinets throughout the apartment, and some were openable (with things you'd want like glassware, washer, etc.) but others were not. Presumably, the locked closets had things that the owner wished to keep separate, but there was no way of knowing which closets were accessible as they were not marked differently in any way. So a search for an item would require attempting to open several cabinets, not knowing if they were just difficult to open or not meant to be opened at all. Surely some sort of mark or sign would be helpful in this regard.
There is a small step-up from the hallway to the kitchen, which because of the pattern of the flooring, is virtually invisible. We tripped on it several times before finally laying something down across it so our eyes would catch it when walking by. It's a small thing, I know, but I point it out as just another "quirk" of this unit.
Finally, I felt the communication was rather lacking. There were lots of carefully timed messages about checking in, checking out, etc. But a request about the possibility of a fan (due to the heat) was initially met by a "I will check" response, and then basically ignored.
The location of the apartment is the best thing by far. On a hill below the castle, the views of Lisbon are spectacular. It is short walking distance to lots of the best neighborhoods in Lisbon, though (like all the city) there are lots of stairs and hills to traverse.