Excellent apartment: good price to quality ratio, location right in the center of Lisbon, everything that is needed is there, even a dishwasher. The bed is large even for two people and there is also a couch in case it is needed.
I should warn though, that the stairs are steep, which is not a problem for me, but may be a problem for the elderly.
The apartment owner is always accessible and really nice, I had no problems with him whatsoever.
All in all it's a good option to stay in the center of Lisbon for a few days.