With my wife, we stayed for almost two months at the place and we loved it.
It's just big enough for two, well prepared, with lovely touches here and there. It felt at home straight away, it had all the required amenities, well-equipped kitchen(though small) and quite good wifi(very seldom glitches were quickly sorted with router restart). It felt so good that at times we preferred to chill out in the apartment rather go and explore the Lisbon, which is definitely worth exploring.
The location was exactly how we wanted. Not far from touristic areas, but not quite in it. With bus, tram and metro stations not too far away.
Definitely will recommend the place with exceptional Fernanda's hospitality.
Oh, and check-in/check-out was extremely flexible, huge thanks to Fernanda for that too.