The apartment itself is lovely, bright, spacious, and in an unbeatable location -- you're literally 2 steps away from the Avenida metro stop on the Blue Line, and 10min away from the Rossio train station, 15min from Baixa/Chiado and Barrio Alto, 20min from the Tejo riverfront, yet away from all the hustle and bustle of nightlife. An added benefit is the use of a parking garage, though I wouldn't recommend having a car in Lisbon :)
However, as it is being managed by a real estate company, it feels sterile and lacks any personal touches. Things that stand out: no closet space in the 2nd bedroom (with 2 twin beds), no hooks in either of the bathrooms, awkward furniture in the living room. The kitchen is nice and well-equipped (save yourself a trip to Pingo Doce by the Rossio station and take the metro to El Corte Ingles for a much better supermarket experience!), includes a Nespresso Machine, microwave, dishwasher, and a washing machine. Beds are comfortable, and double paned windows block out all street noise. A/C Works well and is very quiet. Communication with Cibele (who checked me in) was smooth and quick.
Things to note: the apartment has a tankless water heater, which means water needs to flow for a bit before getting hot -- but the sink in the smaller bathroom never triggers the water heater, so the water continues to come out cold there unless the shower is also turned on.
All in all, it was a decent experience, but I feel that the apartment should be priced cheaper to reflect the true value of this booking.