Absolutely in the middle of the city and a very well equipped apartment. We had to wait 2 hours for the checkin, but it was still ok. We went to the restaurant Casa da India (Rua do Loreto 45), which is 2-3 minutes away from the apartment. I can only recommend it.
This apartment is properly best for younger travellers, who want to experience Lisboa's night life. At around 1 am it quiets down. The kitchen and the living room are located at the ground level (next to a busy staircase) and the both bedrooms are on the second floor.
Everything is within walking distance. Miradouro of the Santa Catarina, the next supermarket (Minipreco) and the tram No. 28 are also only a few minutes away. It takes 10 minutes to get to the city center and the Rossio station, that you take for a trip to Sintra, is 15 minutes away.