The apartment is very nice and it's ideal for one person or a couple. It has plenty of light and an awesome view over the neighborhood and the river.
It's also very well furnished and fully equipped -including a washing machine-, clean and new. The kichen has two stoves, a microwaves, a coffe machine, big fridge, and plenty of pots, plates and so forth.
The stairs of the building are a bit steep, so you must be careful when carrying up the luggage if it's heavy, but otherwise it's fine.
The neihborhood is very nice, full of shops, cafés, bakeries, and restaurants, with two supermarkets nearby.
The city center (Baixa-Chiado) is also easily reachable by foot (although this city is hilly and you'll have to go up and down often!) and the cool tram 28 stops near the house and takes you all the way to Chiado and Bairro Alto through Alfama. Also Alfama and Mouraria are very close and full of nice spots to see, and Santa Apolónia subway and train station is not far down the street.
The building is also quiet and it's a nice place to sleep or get some rest. Twice a week there's a famous fair down the street.
I totally recommend staying here!