The location is great. About 8 minutes walking from Sao Bento Station. This means you will have quick access to all type of transportation (i.e. subways, buses, tour buses, ways to airport via mass transit and train to other cities).
The apartment is located uphill, easy to go up without suitcases. Add those rolling carry-on and you will loose some important calories (now we are over 60 years of age). Alternatively, leaving the apartment to the left you will arrive at the Praca Da Batalha (3 minutes away). Easier access to other transportation, coffee shops and activities.
The apartment is beautiful, clean and very comfortable. A few points to consider:
1) Be aware foreigners (specially North Americans and Brazilians) In Portugal beds are not made with two sheets (only mattress sheet - no top sheet). The tops are comforters with a cover (all very clean).
2) The master bedroom presented a problem with a strong bad smell (probably sewer problems) coming from the master bathroom. The host were very responsive and addressed the issue but only temporarily. Unfortunately, at the end of the following day the smell returned. There is a separate powder room that helped. You might want to ask the host if they found a more permanent solution.
3) Also, the same bathroom has a low arch to access the toilet. Had I not hung a towel in the middle of the arch I inadvertently would have hit my head several times.
4) If you are staying for more than a few days, make sure to plan a visit to a local supermarket for paper towels and some extra coffee pods (if you care for them).
Enjoy your staying.