Exactly as in the pictures, the apartment is clean and bright. It also feels very safe, there are electric shutters on the windows, the door to the apartment is a massive security door and the main door to the apartments has an electric code. We didn't cook ourselves whilst there but the kitchen wasn't lacking in utensils. The bathroom was nice and spacious, the only downside for us was that the shower is hand-held only, but this is a minor point.
Matilde's parents met us promptly on check-in and were communicative throughout. They showed us around the apartment and talked us through a table of leaflets recommending things to do in the city, including a map. They had also left a few snacks in the kitchen and a bottle of wine in the fridge which was a lovely touch. You must check-out by 11am and they do not allow you to leave bags there for the day if you have a later flight, but they showed us somewhere in the city to store our bags for the day (which we did, and it was a great recommendation, not expensive and you could print boarding passes there for free too).
The location is quiet and safe. It is a 15 minute walk to Barrio Alto, 20-25 minute walk to the "centre" and about a 20 minute walk to the Timeout Market and the train station which will take you to Belem and Cascais. We walked everywhere when we stayed here, which was great. However, it is worth noting that Lisbon is very hilly and, especially if it's very hot, the uphills can be a little exhausting. There is a tram stop near to the apartment so you don't have to walk everywhere, although we only used this once as the experience wasn't that pleasant (very full and crowded).
Overall it was a nice apartment and good for a stay in Lisbon. The hosts were thoughtful and communicative, the apartment was clean and it's nice that you're able to walk most places from the location.