We spent five nights in the apartment and enjoyed it. It is a great place to stay for two people.
Location. The apartment is located on the first floor (one floor above the street level) of a historic building on a street that connects Avenida da Libertade district with the up-the-hill districts of Bairro Alto and Principe Real. It is a short walk up the hill from the Avenida metro station, or a short walk down the hill from (stairs are available) Praca do Principe Real. Easy 15 minute walk to pretty much anywhere in the center of Lisbon. The location is mostly quiet, but it does get some foot traffic some time between 10pm and midnight. There are a couple of convenience stores and several small restaurants right next to the apartment - the rest of the amenities are on or off the main thoroughfares around it. There are also some theaters in immediate vicinity, and the botanical gardens (albeit the back part).
Parking. We did not need parking for much (just to check in and then return the car to the airport), but.... There is a large parking lot somewhere around, but we did not take advantage of it. It is possible to park for a short time right in front of the apartment - there is a spot there that is kind of on the street bend, so it is rarely occupied. Won't work as a long-term spot (plus, parking is by permit in the neighborhood outside of weekends), but works well for dropping off the luggage.
Apartment. We were contacted with precise instructions on how to get into the apartment, and those instructions were easy to follow. The apartment itself has two bedrooms - one with a double bed, and one with a single bed. The bedrooms overlook the main street. Both bedrooms have windows with blinds - it might not be 100% obvious at first, but we figured them out, and used them throughout our stay. The bedrooms open into a living room equipped with a couch (I think it unfolds, but we didn't need to) and a smart TV. From there, there is a full bath and a fairly large and comfortable eat-in kitchen, with windows overlooking the back yard. There is air conditioning in the apartment and it works well. There is also a washing machine - you can use the strings hanging on the kitchen window to dry clothes, but be careful not to drop them - access to the backyard is somewhat tricky. We appreciated the Nespresso machine as well as a large fridge. The kitchen is well-stocked as well.
This apartment certainly has character and it might be too small for larger groups/families, but for two people it is more than sufficient, and presents excellent value - it is close to everything.