Sergio's place is really very lovely. It's just like the photos, with the beds and overall feel of the apartment being very comfortable, it's a very nice place to come back to after a day of exploring. The location is in a very safe and charming area, it's away from the hustle and bustle of the more touristy parts which is lovely but also means a bit more out of the way. There are great cafe's/restaurants in walking distance but for most places you should get an uber (3/5 euros a pop) or the tram.
But Lisbon is such a beautiful relaxed city I wouldn't worry yourself with travel arrangements too much, just stroll and see what you find.
The rooms are very homely and the living area can be lit to feel very cozy, Sergio's guide book was great to have as a reference point for the days excursions.
Honestly had such a good time here, it's an apartment that takes away all the stress of traveling and just allows you to enjoy your trip.
Definitely recommend!