The apartment is perfectly located: close to shops and the old center. Public transport and the cable cars are easily accessible by foot as well. There is a viewpoint very close by and a little park where you can see the sunrise and sunset. It is very spacious for one or two people altho there is not much storage/closet space for more than one person. (keep that in mind for longer stays) Marco is very helpful, he will accommodate your arrival and departure however he can and has lots of tips and recommendations to discover Lisbon and surrounding areas. He even has suggestions for future travels in Portugal if you are interested. The internet is stable, and the speed is good. The appartment has everything you'd need, all the kitchen utensils, extra blankets, hairdryer and towels.
My only little caveats would be that it lacks cosier lighting (which only really matters in winter as the sun sets earlier), there is no coffee machine/maker and you might need to get some cooking essentials like oil and pepper.
If you are going to be walking around the city a lot, I recommend this place!