As first-time visitors to Lisbon, we couldn't know how convenient the location of Martin's flat was--central to many major sights and monuments, not to mention great food, public transportation of all kinds (metro, tram, buses, trains to Sintra). We felt so well situated for getting anywhere we needed to on foot or by transport.
Martin's flat is very nicely appointed and spacious. The master bedroom had a very comfortable, firm bed with en suite bath; the second bedroom had two twin beds. Occasionally at night the street-facing rooms (living room and second bedroom) could get a little noisy but the soundproofing on the windows helped minimize disturbance. We didn't use the kitchen much other than to make coffee in the mornings but it was more than adequate.
I can recommend a stay at Martin's place without reservation. My review wouldn't be complete without a shout-out to Mafalda and Monica, the kind and efficient ladies who checked us in. All three hosts were extremely responsive.